SEC Info  
    Home      Search      My Interests      Help      Sign In      Please Sign In

Idt Corp – ‘10-Q’ for 1/31/17 – ‘EX-101.DEF’

On:  Monday, 3/13/17, at 5:15pm ET   ·   For:  1/31/17   ·   Accession #:  1213900-17-2245   ·   File #:  1-16371

Previous ‘10-Q’:  ‘10-Q’ on 12/12/16 for 10/31/16   ·   Next:  ‘10-Q’ on 6/9/17 for 4/30/17   ·   Latest:  ‘10-Q’ on 3/11/24 for 1/31/24

Find Words in Filings emoji
 
  in    Show  and   Hints

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

 3/13/17  Idt Corp                          10-Q        1/31/17   68:3.8M                                   Edgar Agents LLC/FA

Quarterly Report   —   Form 10-Q   —   Sect. 13 / 15(d) – SEA’34
Filing Table of Contents

Document/Exhibit                   Description                      Pages   Size 

 1: 10-Q        Quarterly Report                                    HTML    382K 
 2: EX-31.1     Certification -- §302 - SOA'02                      HTML     23K 
 3: EX-31.2     Certification -- §302 - SOA'02                      HTML     23K 
 4: EX-32.1     Certification -- §906 - SOA'02                      HTML     19K 
 5: EX-32.2     Certification -- §906 - SOA'02                      HTML     19K 
12: R1          Document and Entity Information                     HTML     39K 
13: R2          Consolidated Balance Sheets                         HTML    125K 
14: R3          Consolidated Balance Sheets (Parenthetical)         HTML     42K 
15: R4          Consolidated Statements of Income (Unaudited)       HTML     80K 
16: R5          Consolidated Statements of Comprehensive Income     HTML     44K 
                (Unaudited)                                                      
17: R6          Consolidated Statements of Cash Flows (Unaudited)   HTML    117K 
18: R7          Basis of Presentation                               HTML     24K 
19: R8          Zedge Spin-Off                                      HTML     31K 
20: R9          Investment in Cornerstone Pharmaceuticals, Inc.     HTML     30K 
21: R10         Marketable Securities                               HTML     59K 
22: R11         Fair Value Measurements                             HTML     40K 
23: R12         Derivative Instruments                              HTML     35K 
24: R13         Equity                                              HTML     47K 
25: R14         Earnings Per Share                                  HTML     36K 
26: R15         Revolving Credit Loan Payable                       HTML     24K 
27: R16         Accrued Severance Expense                           HTML     21K 
28: R17         Accumulated Other Comprehensive Loss                HTML     32K 
29: R18         Business Segment Information                        HTML     51K 
30: R19         Commitments and Contingencies                       HTML     41K 
31: R20         Other (Expense) Income, Net                         HTML     28K 
32: R21         Income Taxes                                        HTML     23K 
33: R22         Recently Issued Accounting Standard Not Yet         HTML     32K 
                Adopted                                                          
34: R23         Zedge Spin-Off (Tables)                             HTML     26K 
35: R24         Marketable Securities (Tables)                      HTML     87K 
36: R25         Fair Value Measurements (Tables)                    HTML     36K 
37: R26         Derivative Instruments (Tables)                     HTML     25K 
38: R27         Equity (Tables)                                     HTML     40K 
39: R28         Earnings Per Share (Tables)                         HTML     45K 
40: R29         Accumulated Other Comprehensive Loss (Tables)       HTML     27K 
41: R30         Business Segment Information (Tables)               HTML     60K 
42: R31         Commitments and Contingencies (Tables)              HTML     28K 
43: R32         Other (Expense) Income, Net (Tables)                HTML     31K 
44: R33         Zedge Spin-Off (Details)                            HTML     27K 
45: R34         Investment in Cornerstone Pharmaceuticals, Inc.     HTML     87K 
                (Details)                                                        
46: R35         Marketable Securities (Details)                     HTML     64K 
47: R36         Marketable Securities (Details 1)                   HTML     34K 
48: R37         Marketable Securities (Details 2)                   HTML     44K 
49: R38         Marketable Securities (Details Textual)             HTML     38K 
50: R39         Fair Value Measurements (Details)                   HTML     30K 
51: R40         Fair Value Measurements (Details Textual)           HTML     22K 
52: R41         Derivative Instruments (Details)                    HTML     21K 
53: R42         Equity (Details)                                    HTML     62K 
54: R43         Equity (Details Textual)                            HTML     60K 
55: R44         Earnings Per Share (Details)                        HTML     33K 
56: R45         Earnings Per Share (Details 1)                      HTML     22K 
57: R46         Revolving Credit Loan Payable (Details)             HTML     46K 
58: R47         Accrued Severance Expense (Details)                 HTML     26K 
59: R48         Accumulated Other Comprehensive Loss (Details)      HTML     48K 
60: R49         Business Segment Information (Details)              HTML     42K 
61: R50         Business Segment Information (Details Textual)      HTML     20K 
62: R51         Commitments and Contingencies (Details)             HTML     28K 
63: R52         Commitments and Contingencies (Details Textual)     HTML     40K 
64: R53         Other (Expense) Income, Net (Details)               HTML     33K 
65: R54         Income Taxes (Details)                              HTML     24K 
67: XML         IDEA XML File -- Filing Summary                      XML    117K 
66: EXCEL       IDEA Workbook of Financial Reports                  XLSX     61K 
 6: EX-101.INS  XBRL Instance -- idt-20170131                        XML   1.04M 
 8: EX-101.CAL  XBRL Calculations -- idt-20170131_cal                XML    137K 
 9: EX-101.DEF  XBRL Definitions -- idt-20170131_def                 XML    382K 
10: EX-101.LAB  XBRL Labels -- idt-20170131_lab                      XML    931K 
11: EX-101.PRE  XBRL Presentations -- idt-20170131_pre               XML    600K 
 7: EX-101.SCH  XBRL Schema -- idt-20170131                          XSD    127K 
68: ZIP         XBRL Zipped Folder -- 0001213900-17-002245-xbrl      Zip    100K 


‘EX-101.DEF’   —   XBRL Definitions — idt-20170131_def


This Exhibit is an XBRL XML File.


                                                                                                                                                                                
<?xml version="1.0" encoding="windows-1252"?>
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:xbrldt="http://xbrl.org/2005/xbrldt">
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/notAll" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#notAll"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#DocumentandEntityInformation" roleURI="http://www.idt.net/role/DocumentandEntityInformation"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#ConsolidatedBalanceSheets" roleURI="http://www.idt.net/role/ConsolidatedBalanceSheets"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#ConsolidatedBalanceSheetsParenthetical" roleURI="http://www.idt.net/role/ConsolidatedBalanceSheetsParenthetical"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#ZedgeSpinOffDetails" roleURI="http://www.idt.net/role/ZedgeSpinOffDetails"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#InvestmentincornerstonepharmaceuticalsincDetails" roleURI="http://www.idt.net/role/InvestmentincornerstonepharmaceuticalsincDetails"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#MarketableSecuritiesDetails" roleURI="http://www.idt.net/role/MarketableSecuritiesDetails"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#MarketableSecuritiesDetails2" roleURI="http://www.idt.net/role/MarketableSecuritiesDetails2"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#MarketableSecuritiesDetailsTextual" roleURI="http://www.idt.net/role/MarketableSecuritiesDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#FairValueMeasurementsDetails" roleURI="http://www.idt.net/role/FairValueMeasurementsDetails"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#EquityDetails" roleURI="http://www.idt.net/role/EquityDetails"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#EquityDetailsTextual" roleURI="http://www.idt.net/role/EquityDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#RevolvingCreditLoanPayableDetails" roleURI="http://www.idt.net/role/RevolvingCreditLoanPayableDetails"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#AccruedSeveranceExpenseDetails" roleURI="http://www.idt.net/role/AccruedSeveranceExpenseDetails"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#AccumulatedOtherComprehensiveLossDetails" roleURI="http://www.idt.net/role/AccumulatedOtherComprehensiveLossDetails"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#BusinessSegmentInformationDetails" roleURI="http://www.idt.net/role/BusinessSegmentInformationDetails"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#CommitmentsAndContingenciesDetails" roleURI="http://www.idt.net/role/CommitmentsAndContingenciesDetails"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#CommitmentsAndContingenciesDetailsTextual" roleURI="http://www.idt.net/role/CommitmentsAndContingenciesDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="idt-20170131.xsd#IncomeTaxesDetails" roleURI="http://www.idt.net/role/IncomeTaxesDetails"/>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/DocumentandEntityInformation">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_StatementTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_1" xlink:to="loc_us-gaap_StatementClassOfStockAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2" xlink:to="loc_us-gaap_ClassOfStockDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2" xlink:to="loc_us-gaap_ClassOfStockDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_3" xlink:to="loc_us-gaap_CommonClassAMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonClassBMember" xlink:label="loc_us-gaap_CommonClassBMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_3" xlink:to="loc_us-gaap_CommonClassBMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityRegistrantName" xlink:label="loc_dei_EntityRegistrantName_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_dei_EntityRegistrantName_6" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityCentralIndexKey" xlink:label="loc_dei_EntityCentralIndexKey_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_dei_EntityCentralIndexKey_7" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_AmendmentFlag" xlink:label="loc_dei_AmendmentFlag_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_dei_AmendmentFlag_8" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_CurrentFiscalYearEndDate" xlink:label="loc_dei_CurrentFiscalYearEndDate_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_dei_CurrentFiscalYearEndDate_9" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_DocumentType" xlink:label="loc_dei_DocumentType_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_dei_DocumentType_10" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_DocumentPeriodEndDate" xlink:label="loc_dei_DocumentPeriodEndDate_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_dei_DocumentPeriodEndDate_11" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_DocumentFiscalYearFocus" xlink:label="loc_dei_DocumentFiscalYearFocus_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_dei_DocumentFiscalYearFocus_12" order="70" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_DocumentFiscalPeriodFocus" xlink:label="loc_dei_DocumentFiscalPeriodFocus_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_dei_DocumentFiscalPeriodFocus_13" order="80" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityFilerCategory" xlink:label="loc_dei_EntityFilerCategory_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_dei_EntityFilerCategory_14" order="90" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityCommonStockSharesOutstanding" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_15"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_15" order="100" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/ConsolidatedBalanceSheets">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_StatementTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_1" xlink:to="loc_us-gaap_StatementClassOfStockAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2" xlink:to="loc_us-gaap_ClassOfStockDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2" xlink:to="loc_us-gaap_ClassOfStockDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_3" xlink:to="loc_us-gaap_CommonClassAMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonClassBMember" xlink:label="loc_us-gaap_CommonClassBMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_3" xlink:to="loc_us-gaap_CommonClassBMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsAbstract" xlink:label="loc_us-gaap_AssetsAbstract_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_AssetsAbstract_6" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="loc_us-gaap_AssetsCurrentAbstract_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_6" xlink:to="loc_us-gaap_AssetsCurrentAbstract_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_7" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_8" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_7" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_9" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MarketableSecuritiesCurrent" xlink:label="loc_us-gaap_MarketableSecuritiesCurrent_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_7" xlink:to="loc_us-gaap_MarketableSecuritiesCurrent_10" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReceivablesNetCurrent" xlink:label="loc_us-gaap_ReceivablesNetCurrent_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_7" xlink:to="loc_us-gaap_ReceivablesNetCurrent_11" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PrepaidExpenseCurrent" xlink:label="loc_us-gaap_PrepaidExpenseCurrent_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_7" xlink:to="loc_us-gaap_PrepaidExpenseCurrent_12" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:label="loc_us-gaap_OtherAssetsCurrent_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_7" xlink:to="loc_us-gaap_OtherAssetsCurrent_13" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaap_AssetsCurrent_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_7" xlink:to="loc_us-gaap_AssetsCurrent_14" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_15"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_6" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_15" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_16"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_6" xlink:to="loc_us-gaap_Goodwill_16" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_17"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_6" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_17" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermInvestments" xlink:label="loc_us-gaap_LongTermInvestments_18"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_6" xlink:to="loc_us-gaap_LongTermInvestments_18" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxAssetsNetNoncurrent" xlink:label="loc_us-gaap_DeferredTaxAssetsNetNoncurrent_19"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_6" xlink:to="loc_us-gaap_DeferredTaxAssetsNetNoncurrent_19" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_20"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_6" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_20" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_21"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_6" xlink:to="loc_us-gaap_Assets_21" order="70" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_22"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_22" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_23"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_22" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_23" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaap_AccountsPayableCurrent_24"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_23" xlink:to="loc_us-gaap_AccountsPayableCurrent_24" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_25"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_23" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_25" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredRevenueCurrent" xlink:label="loc_us-gaap_DeferredRevenueCurrent_26"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_23" xlink:to="loc_us-gaap_DeferredRevenueCurrent_26" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CustomerDepositsCurrent" xlink:label="loc_us-gaap_CustomerDepositsCurrent_27"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_23" xlink:to="loc_us-gaap_CustomerDepositsCurrent_27" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccruedIncomeTaxesCurrent" xlink:label="loc_us-gaap_AccruedIncomeTaxesCurrent_28"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_23" xlink:to="loc_us-gaap_AccruedIncomeTaxesCurrent_28" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherLiabilitiesCurrent" xlink:label="loc_us-gaap_OtherLiabilitiesCurrent_29"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_23" xlink:to="loc_us-gaap_OtherLiabilitiesCurrent_29" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaap_LiabilitiesCurrent_30"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_23" xlink:to="loc_us-gaap_LiabilitiesCurrent_30" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_31"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_22" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_31" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaap_Liabilities_32"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_22" xlink:to="loc_us-gaap_Liabilities_32" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="loc_us-gaap_CommitmentsAndContingencies_33"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_22" xlink:to="loc_us-gaap_CommitmentsAndContingencies_33" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquityAbstract" xlink:label="loc_us-gaap_StockholdersEquityAbstract_34"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_22" xlink:to="loc_us-gaap_StockholdersEquityAbstract_34" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="loc_us-gaap_PreferredStockValue_35"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_34" xlink:to="loc_us-gaap_PreferredStockValue_35" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockValue" xlink:label="loc_us-gaap_CommonStockValue_36"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_34" xlink:to="loc_us-gaap_CommonStockValue_36" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="loc_us-gaap_AdditionalPaidInCapital_37"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_34" xlink:to="loc_us-gaap_AdditionalPaidInCapital_37" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TreasuryStockValue" xlink:label="loc_us-gaap_TreasuryStockValue_38"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_34" xlink:to="loc_us-gaap_TreasuryStockValue_38" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_39"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_34" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_39" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_40"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_34" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_40" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_41"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_34" xlink:to="loc_us-gaap_StockholdersEquity_41" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinorityInterest" xlink:label="loc_us-gaap_MinorityInterest_42"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_22" xlink:to="loc_us-gaap_MinorityInterest_42" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_43"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_22" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_43" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_44"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_22" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_44" order="70" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/ConsolidatedBalanceSheetsParenthetical">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_StatementTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_1" xlink:to="loc_us-gaap_StatementClassOfStockAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2" xlink:to="loc_us-gaap_ClassOfStockDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2" xlink:to="loc_us-gaap_ClassOfStockDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_3" xlink:to="loc_us-gaap_CommonClassAMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonClassBMember" xlink:label="loc_us-gaap_CommonClassBMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_3" xlink:to="loc_us-gaap_CommonClassBMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_6" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_7" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_8" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaap_PreferredStockSharesIssued_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_PreferredStockSharesIssued_9" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_10" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_11" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaap_CommonStockSharesIssued_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_CommonStockSharesIssued_12" order="70" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_13" order="80" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TreasuryStockShares" xlink:label="loc_us-gaap_TreasuryStockShares_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_TreasuryStockShares_14" order="90" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/ZedgeSpinOffDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfSubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipTable" xlink:label="loc_us-gaap_ScheduleOfSubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0" xlink:to="loc_us-gaap_ScheduleOfSubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipTable_1" xlink:to="loc_dei_LegalEntityAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_2" xlink:to="loc_dei_EntityDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_2" xlink:to="loc_dei_EntityDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_ZedgeMember" xlink:label="loc_idt_ZedgeMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_3" xlink:to="loc_idt_ZedgeMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItem" xlink:label="loc_idt_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItem_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0" xlink:to="loc_idt_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItem_6" order="20" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/InvestmentincornerstonepharmaceuticalsincDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InvestmentHoldingsLineItems" xlink:label="loc_us-gaap_InvestmentHoldingsLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfInvestmentsTable" xlink:label="loc_us-gaap_ScheduleOfInvestmentsTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_InvestmentHoldingsLineItems_0" xlink:to="loc_us-gaap_ScheduleOfInvestmentsTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentAxis" xlink:label="loc_invest_InvestmentAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfInvestmentsTable_1" xlink:to="loc_invest_InvestmentAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentDomain" xlink:label="loc_invest_InvestmentDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_invest_InvestmentAxis_2" xlink:to="loc_invest_InvestmentDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentDomain" xlink:label="loc_invest_InvestmentDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_invest_InvestmentAxis_2" xlink:to="loc_invest_InvestmentDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_CornerstonePharmaceuticalsIncMember" xlink:label="loc_idt_CornerstonePharmaceuticalsIncMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentDomain_3" xlink:to="loc_idt_CornerstonePharmaceuticalsIncMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_CsPharmaHoldingsMember" xlink:label="loc_idt_CsPharmaHoldingsMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentDomain_3" xlink:to="loc_idt_CsPharmaHoldingsMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfInvestmentsTable_1" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_6" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_6" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_7_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_6" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_7_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConvertibleDebtMember" xlink:label="loc_us-gaap_ConvertibleDebtMember_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7" xlink:to="loc_us-gaap_ConvertibleDebtMember_8" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConvertibleNotesPayableMember" xlink:label="loc_us-gaap_ConvertibleNotesPayableMember_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7" xlink:to="loc_us-gaap_ConvertibleNotesPayableMember_9" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_ConvertiblePromissoryNoteMember" xlink:label="loc_idt_ConvertiblePromissoryNoteMember_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7" xlink:to="loc_idt_ConvertiblePromissoryNoteMember_10" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:label="loc_us-gaap_TitleOfIndividualAxis_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfInvestmentsTable_1" xlink:to="loc_us-gaap_TitleOfIndividualAxis_11" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TitleOfIndividualAxis_11" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_12" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_12_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TitleOfIndividualAxis_11" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_12_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_HowardAndDeborahJonasMember" xlink:label="loc_idt_HowardAndDeborahJonasMember_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_12" xlink:to="loc_idt_HowardAndDeborahJonasMember_13" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_HowardSAndDeborahJonasFoundationMember" xlink:label="loc_idt_HowardSAndDeborahJonasFoundationMember_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_12" xlink:to="loc_idt_HowardSAndDeborahJonasFoundationMember_14" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_JonasMember" xlink:label="loc_idt_JonasMember_15"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_12" xlink:to="loc_idt_JonasMember_15" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract" xlink:label="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentHoldingsLineItems_0" xlink:to="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_InitialAmountOfInvestment" xlink:label="loc_idt_InitialAmountOfInvestment_17"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_idt_InitialAmountOfInvestment_17" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_18"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_18" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_19"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_19" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="loc_us-gaap_DebtInstrumentMaturityDate_20"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_us-gaap_DebtInstrumentMaturityDate_20" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_RemainingAmountOfInvestment" xlink:label="loc_idt_RemainingAmountOfInvestment_21"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_idt_RemainingAmountOfInvestment_21" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_PurchaseSharesOfCapitalStock" xlink:label="loc_idt_PurchaseSharesOfCapitalStock_22"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_idt_PurchaseSharesOfCapitalStock_22" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_ExerciseWarrantsValue" xlink:label="loc_idt_ExerciseWarrantsValue_23"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_idt_ExerciseWarrantsValue_23" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_InitialAmountOfInvestmentAmountsPaid" xlink:label="loc_idt_InitialAmountOfInvestmentAmountsPaid_24"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_idt_InitialAmountOfInvestmentAmountsPaid_24" order="70" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentConvertibleTermsOfConversionFeature" xlink:label="loc_us-gaap_DebtInstrumentConvertibleTermsOfConversionFeature_25"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_us-gaap_DebtInstrumentConvertibleTermsOfConversionFeature_25" order="80" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_MaximumAmountToBeInvested" xlink:label="loc_idt_MaximumAmountToBeInvested_26"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_idt_MaximumAmountToBeInvested_26" order="90" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentRepurchaseAgreementAmountToBeReceived" xlink:label="loc_invest_InvestmentRepurchaseAgreementAmountToBeReceived_27"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_invest_InvestmentRepurchaseAgreementAmountToBeReceived_27" order="100" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_ProceedsFromIssuanceOfMemberInterests" xlink:label="loc_idt_ProceedsFromIssuanceOfMemberInterests_28"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_idt_ProceedsFromIssuanceOfMemberInterests_28" order="110" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentWarrantsExpirationDate" xlink:label="loc_invest_InvestmentWarrantsExpirationDate_29"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_invest_InvestmentWarrantsExpirationDate_29" order="120" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherLongTermInvestments" xlink:label="loc_us-gaap_OtherLongTermInvestments_30"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_us-gaap_OtherLongTermInvestments_30" order="130" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount" xlink:label="loc_us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount_31"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount_31" order="140" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_32"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_32" order="150" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_OtherCurrentLiabilities" xlink:label="loc_idt_OtherCurrentLiabilities_33"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_idt_OtherCurrentLiabilities_33" order="160" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_ProceedsFromThirdPartyMemberInterestsDescription" xlink:label="loc_idt_ProceedsFromThirdPartyMemberInterestsDescription_34"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_idt_ProceedsFromThirdPartyMemberInterestsDescription_34" order="170" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_InvestmentWarrantsExerciseTermsAndExpiration" xlink:label="loc_idt_InvestmentWarrantsExerciseTermsAndExpiration_35"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_idt_InvestmentWarrantsExerciseTermsAndExpiration_35" order="180" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConvertibleNotesPayable" xlink:label="loc_us-gaap_ConvertibleNotesPayable_36"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_us-gaap_ConvertibleNotesPayable_36" order="190" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_PercentageOfDirectAndIndirectInterest" xlink:label="loc_idt_PercentageOfDirectAndIndirectInterest_37"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_idt_PercentageOfDirectAndIndirectInterest_37" order="200" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromSaleOfInterestInCorporateUnit" xlink:label="loc_us-gaap_ProceedsFromSaleOfInterestInCorporateUnit_38"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_InvestmentInCornerstonePharmaceuticalsIncTextualAbstract_16" xlink:to="loc_us-gaap_ProceedsFromSaleOfInterestInCorporateUnit_38" order="210" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/MarketableSecuritiesDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesTable" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0" xlink:to="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_1" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_2" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_2" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CertificatesOfDepositMember" xlink:label="loc_us-gaap_CertificatesOfDepositMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_us-gaap_CertificatesOfDepositMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FederalHomeLoanBankCertificatesAndObligationsFHLBMember" xlink:label="loc_us-gaap_FederalHomeLoanBankCertificatesAndObligationsFHLBMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_us-gaap_FederalHomeLoanBankCertificatesAndObligationsFHLBMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember" xlink:label="loc_us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember_6" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_7" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_InternationalAgencyNotesMember" xlink:label="loc_idt_InternationalAgencyNotesMember_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_idt_InternationalAgencyNotesMember_8" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_MutualFundsMember" xlink:label="loc_idt_MutualFundsMember_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_idt_MutualFundsMember_9" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CorporateBondSecuritiesMember" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_us-gaap_CorporateBondSecuritiesMember_10" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquitySecuritiesMember" xlink:label="loc_us-gaap_EquitySecuritiesMember_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_us-gaap_EquitySecuritiesMember_11" order="70" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_USTreasuryNotesSecuritiesMember" xlink:label="loc_us-gaap_USTreasuryNotesSecuritiesMember_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_us-gaap_USTreasuryNotesSecuritiesMember_12" order="80" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MunicipalBondsMember" xlink:label="loc_us-gaap_MunicipalBondsMember_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_us-gaap_MunicipalBondsMember_13" order="90" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecuritiesCurrentAbstract" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesCurrentAbstract_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesCurrentAbstract_14" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecuritiesAmortizedCost" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_15"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesCurrentAbstract_14" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_15" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_16"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesCurrentAbstract_14" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_16" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_17"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesCurrentAbstract_14" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_17" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedGainBeforeTax" xlink:label="loc_us-gaap_AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedGainBeforeTax_18"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesCurrentAbstract_14" xlink:to="loc_us-gaap_AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedGainBeforeTax_18" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedLossBeforeTax" xlink:label="loc_us-gaap_AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedLossBeforeTax_19"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesCurrentAbstract_14" xlink:to="loc_us-gaap_AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedLossBeforeTax_19" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_AvailableForSaleSecuritiesTotalGrossUnrealizedGains" xlink:label="loc_idt_AvailableForSaleSecuritiesTotalGrossUnrealizedGains_20"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesCurrentAbstract_14" xlink:to="loc_idt_AvailableForSaleSecuritiesTotalGrossUnrealizedGains_20" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_AvailableForSaleSecuritiesTotalGrossUnrealizedLosses" xlink:label="loc_idt_AvailableForSaleSecuritiesTotalGrossUnrealizedLosses_21"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesCurrentAbstract_14" xlink:to="loc_idt_AvailableForSaleSecuritiesTotalGrossUnrealizedLosses_21" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MarketableSecuritiesCurrent" xlink:label="loc_us-gaap_MarketableSecuritiesCurrent_22"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesCurrentAbstract_14" xlink:to="loc_us-gaap_MarketableSecuritiesCurrent_22" order="70" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/MarketableSecuritiesDetails2">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesTable" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0" xlink:to="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_1" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_2" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_2" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CertificatesOfDepositMember" xlink:label="loc_us-gaap_CertificatesOfDepositMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_us-gaap_CertificatesOfDepositMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_InternationalAgencyNotesMember" xlink:label="loc_idt_InternationalAgencyNotesMember_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_idt_InternationalAgencyNotesMember_6" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_MutualFundsMember" xlink:label="loc_idt_MutualFundsMember_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_idt_MutualFundsMember_7" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CorporateBondSecuritiesMember" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_us-gaap_CorporateBondSecuritiesMember_8" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_9" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MunicipalBondsMember" xlink:label="loc_us-gaap_MunicipalBondsMember_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_us-gaap_MunicipalBondsMember_10" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquitySecuritiesMember" xlink:label="loc_us-gaap_EquitySecuritiesMember_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_3" xlink:to="loc_us-gaap_EquitySecuritiesMember_11" order="70" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss_12" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue_13" order="20" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/MarketableSecuritiesDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesTable" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0" xlink:to="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_1" xlink:to="loc_dei_LegalEntityAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_2" xlink:to="loc_dei_EntityDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_2" xlink:to="loc_dei_EntityDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_ZedgeMember" xlink:label="loc_idt_ZedgeMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_3" xlink:to="loc_idt_ZedgeMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_MarketableSecuritiesTextualAbstract" xlink:label="loc_idt_MarketableSecuritiesTextualAbstract_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0" xlink:to="loc_idt_MarketableSecuritiesTextualAbstract_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_NumberOfRelatedPartySharesReceivedInConnectionWithRestrictedStock" xlink:label="loc_idt_NumberOfRelatedPartySharesReceivedInConnectionWithRestrictedStock_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_MarketableSecuritiesTextualAbstract_5" xlink:to="loc_idt_NumberOfRelatedPartySharesReceivedInConnectionWithRestrictedStock_6" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_AmountPaidForRelatedPartySharesReceivedInConnectionWithRestrictedStock" xlink:label="loc_idt_AmountPaidForRelatedPartySharesReceivedInConnectionWithRestrictedStock_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_MarketableSecuritiesTextualAbstract_5" xlink:to="loc_idt_AmountPaidForRelatedPartySharesReceivedInConnectionWithRestrictedStock_7" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InvestmentOwnedAtFairValue" xlink:label="loc_us-gaap_InvestmentOwnedAtFairValue_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_MarketableSecuritiesTextualAbstract_5" xlink:to="loc_us-gaap_InvestmentOwnedAtFairValue_8" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities" xlink:label="loc_us-gaap_ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_MarketableSecuritiesTextualAbstract_5" xlink:to="loc_us-gaap_ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities_9" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecuritiesGrossRealizedGains" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesGrossRealizedGains_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_MarketableSecuritiesTextualAbstract_5" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesGrossRealizedGains_10" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_MarketableSecuritiesTextualAbstract_5" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_11" order="50" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/FairValueMeasurementsDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_3" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_8" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_9" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsFairValueDisclosureAbstract" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_10" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MarketableSecuritiesCurrent" xlink:label="loc_us-gaap_MarketableSecuritiesCurrent_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_10" xlink:to="loc_us-gaap_MarketableSecuritiesCurrent_11" order="0" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/EquityDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_StatementTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_1" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_2" xlink:to="loc_us-gaap_EquityComponentDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_2" xlink:to="loc_us-gaap_EquityComponentDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ParentMember" xlink:label="loc_us-gaap_ParentMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3" xlink:to="loc_us-gaap_ParentMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NoncontrollingInterestMember" xlink:label="loc_us-gaap_NoncontrollingInterestMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3" xlink:to="loc_us-gaap_NoncontrollingInterestMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_6" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_6" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DividendsCash" xlink:label="loc_us-gaap_DividendsCash_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_6" xlink:to="loc_us-gaap_DividendsCash_8" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_RepurchaseOfRestrictedStock" xlink:label="loc_idt_RepurchaseOfRestrictedStock_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_6" xlink:to="loc_idt_RepurchaseOfRestrictedStock_9" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_6" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_10" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_6" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_11" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_DistributionToNoncontrollingInterests" xlink:label="loc_idt_DistributionToNoncontrollingInterests_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_6" xlink:to="loc_idt_DistributionToNoncontrollingInterests_12" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_StockBasedCompensation" xlink:label="loc_idt_StockBasedCompensation_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_6" xlink:to="loc_idt_StockBasedCompensation_13" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTaxAbstract" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_6" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_14" order="70" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProfitLoss" xlink:label="loc_us-gaap_ProfitLoss_15"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_14" xlink:to="loc_us-gaap_ProfitLoss_15" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_16"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_14" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_16" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_17"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_14" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_17" order="20" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/EquityDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfStockLineItems" xlink:label="loc_us-gaap_ClassOfStockLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1" xlink:to="loc_us-gaap_StatementClassOfStockAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2" xlink:to="loc_us-gaap_ClassOfStockDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2" xlink:to="loc_us-gaap_ClassOfStockDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_3" xlink:to="loc_us-gaap_CommonClassAMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonClassBMember" xlink:label="loc_us-gaap_CommonClassBMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_3" xlink:to="loc_us-gaap_CommonClassBMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_6" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_6" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_7_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_6" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_7_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_7" xlink:to="loc_us-gaap_SubsequentEventMember_8" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:label="loc_us-gaap_TitleOfIndividualAxis_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1" xlink:to="loc_us-gaap_TitleOfIndividualAxis_9" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TitleOfIndividualAxis_9" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_10" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_10_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TitleOfIndividualAxis_9" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_10_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_EmployeeMember" xlink:label="loc_idt_EmployeeMember_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_10" xlink:to="loc_idt_EmployeeMember_11" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DividendsCommonStockCash" xlink:label="loc_us-gaap_DividendsCommonStockCash_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_DividendsCommonStockCash_12" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockDividendsPerShareCashPaid" xlink:label="loc_us-gaap_CommonStockDividendsPerShareCashPaid_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_CommonStockDividendsPerShareCashPaid_13" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DividendsPayableAmountPerShare" xlink:label="loc_us-gaap_DividendsPayableAmountPerShare_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_DividendsPayableAmountPerShare_14" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DividendPayableDateToBePaidDayMonthAndYear" xlink:label="loc_us-gaap_DividendPayableDateToBePaidDayMonthAndYear_15"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_DividendPayableDateToBePaidDayMonthAndYear_15" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DividendsPayableDateOfRecordDayMonthAndYear" xlink:label="loc_us-gaap_DividendsPayableDateOfRecordDayMonthAndYear_16"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_DividendsPayableDateOfRecordDayMonthAndYear_16" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased" xlink:label="loc_us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased_17"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased_17" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased_18"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased_18" order="70" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_19"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_19" order="80" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TreasuryStockSharesAcquired" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_20"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_20" order="90" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_21"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_21" order="100" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_22"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_22" order="110" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_23"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_23" order="120" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/RevolvingCreditLoanPayableDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0" xlink:to="loc_us-gaap_DebtInstrumentTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityAxis" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_1" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_2" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_2" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_JulyTwelveTwoThousandTwelveMember" xlink:label="loc_idt_JulyTwelveTwoThousandTwelveMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_3" xlink:to="loc_idt_JulyTwelveTwoThousandTwelveMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PrimeRateMember" xlink:label="loc_us-gaap_PrimeRateMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_3" xlink:to="loc_us-gaap_PrimeRateMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_1" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_6" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_6" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_7_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_6" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_7_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditMember" xlink:label="loc_us-gaap_LineOfCreditMember_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_7" xlink:to="loc_us-gaap_LineOfCreditMember_8" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_9" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_10" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityExpirationDate1" xlink:label="loc_us-gaap_LineOfCreditFacilityExpirationDate1_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0" xlink:to="loc_us-gaap_LineOfCreditFacilityExpirationDate1_11" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShortTermBankLoansAndNotesPayable" xlink:label="loc_us-gaap_ShortTermBankLoansAndNotesPayable_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0" xlink:to="loc_us-gaap_ShortTermBankLoansAndNotesPayable_12" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_13" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_LineOfCreditCovenantMaximumAmountOfLoansAndAdvancesToAffiliatesOrSubsidiaries" xlink:label="loc_idt_LineOfCreditCovenantMaximumAmountOfLoansAndAdvancesToAffiliatesOrSubsidiaries_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0" xlink:to="loc_idt_LineOfCreditCovenantMaximumAmountOfLoansAndAdvancesToAffiliatesOrSubsidiaries_14" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_InvestmentsInAndAdvancesToAffiliates" xlink:label="loc_idt_InvestmentsInAndAdvancesToAffiliates_15"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0" xlink:to="loc_idt_InvestmentsInAndAdvancesToAffiliates_15" order="70" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_LineOfCreditUtilizedForLettersOfCreditOutstandingAmount" xlink:label="loc_idt_LineOfCreditUtilizedForLettersOfCreditOutstandingAmount_16"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0" xlink:to="loc_idt_LineOfCreditUtilizedForLettersOfCreditOutstandingAmount_16" order="80" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateDescription" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateDescription_17"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateDescription_17" order="90" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_BasisPointsSpread" xlink:label="loc_idt_BasisPointsSpread_18"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0" xlink:to="loc_idt_BasisPointsSpread_18" order="100" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/AccruedSeveranceExpenseDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_1" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_2" xlink:to="loc_us-gaap_SegmentDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_2" xlink:to="loc_us-gaap_SegmentDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_WorkforceReductionMember" xlink:label="loc_idt_WorkforceReductionMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_3" xlink:to="loc_idt_WorkforceReductionMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_SeveranceExpenseTextualAbstract" xlink:label="loc_idt_SeveranceExpenseTextualAbstract_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0" xlink:to="loc_idt_SeveranceExpenseTextualAbstract_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SeveranceCosts1" xlink:label="loc_us-gaap_SeveranceCosts1_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_SeveranceExpenseTextualAbstract_5" xlink:to="loc_us-gaap_SeveranceCosts1_6" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_SeveranceExpenseTextualAbstract_5" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent_7" order="10" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/AccumulatedOtherComprehensiveLossDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_0" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_1" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_2" xlink:to="loc_us-gaap_EquityComponentDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_2" xlink:to="loc_us-gaap_EquityComponentDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember" xlink:label="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3" xlink:to="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccumulatedTranslationAdjustmentMember" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_6" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_1" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_7" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_7" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_8" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_8_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_7" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_8_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpenseMember" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpenseMember_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_8" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpenseMember_9" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_0" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_10" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_0" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_11" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_0" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_12" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_0" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_13" order="40" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/BusinessSegmentInformationDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_1" xlink:to="loc_us-gaap_ConsolidationItemsAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_2" xlink:to="loc_us-gaap_ConsolidationItemsDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_2" xlink:to="loc_us-gaap_ConsolidationItemsDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_3" xlink:to="loc_us-gaap_OperatingSegmentsMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_1" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_5" xlink:to="loc_us-gaap_SegmentDomain_6" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_6_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_5" xlink:to="loc_us-gaap_SegmentDomain_6_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_TelecomPlatformServicesMember" xlink:label="loc_idt_TelecomPlatformServicesMember_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_6" xlink:to="loc_idt_TelecomPlatformServicesMember_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_UnifiedCommunicationsAsServiceMember" xlink:label="loc_idt_UnifiedCommunicationsAsServiceMember_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_6" xlink:to="loc_idt_UnifiedCommunicationsAsServiceMember_8" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_ConsumerPhoneServicesMember" xlink:label="loc_idt_ConsumerPhoneServicesMember_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_6" xlink:to="loc_idt_ConsumerPhoneServicesMember_9" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_AllOtherMember" xlink:label="loc_idt_AllOtherMember_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_6" xlink:to="loc_idt_AllOtherMember_10" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CorporateMember" xlink:label="loc_us-gaap_CorporateMember_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_6" xlink:to="loc_us-gaap_CorporateMember_11" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0" xlink:to="loc_us-gaap_Revenues_12" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0" xlink:to="loc_us-gaap_OperatingIncomeLoss_13" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherGeneralExpense" xlink:label="loc_us-gaap_OtherGeneralExpense_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0" xlink:to="loc_us-gaap_OtherGeneralExpense_14" order="30" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/CommitmentsAndContingenciesDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsItemsLineItems" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsItemsLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfRestrictedCashAndCashEquivalentsTable" xlink:label="loc_us-gaap_ScheduleOfRestrictedCashAndCashEquivalentsTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsItemsLineItems_0" xlink:to="loc_us-gaap_ScheduleOfRestrictedCashAndCashEquivalentsTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestrictedCashAndCashEquivalentsTable_1" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_2" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_2" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_IDTFinancialServicesCustomerDepositsMember" xlink:label="loc_idt_IDTFinancialServicesCustomerDepositsMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_3" xlink:to="loc_idt_IDTFinancialServicesCustomerDepositsMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_RelatedLettersOfCreditMember" xlink:label="loc_idt_RelatedLettersOfCreditMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_3" xlink:to="loc_idt_RelatedLettersOfCreditMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_RestrictedOtherMember" xlink:label="loc_idt_RestrictedOtherMember_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_3" xlink:to="loc_idt_RestrictedOtherMember_6" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsItemsLineItems_0" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_7" order="10" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/CommitmentsAndContingenciesDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_0" xlink:to="loc_us-gaap_LossContingenciesTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_1" xlink:to="loc_us-gaap_StatementScenarioAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_2" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_2" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_ExpirationDateOneMember" xlink:label="loc_idt_ExpirationDateOneMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_3" xlink:to="loc_idt_ExpirationDateOneMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_1" xlink:to="loc_dei_LegalEntityAxis_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_5" xlink:to="loc_dei_EntityDomain_6" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_6_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_5" xlink:to="loc_dei_EntityDomain_6_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_IdtFinancialServicesLtdMember" xlink:label="loc_idt_IdtFinancialServicesLtdMember_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_6" xlink:to="loc_idt_IdtFinancialServicesLtdMember_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_IdtPaymentServicesAndIdtFinancialServicesLtdMember" xlink:label="loc_idt_IdtPaymentServicesAndIdtFinancialServicesLtdMember_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_6" xlink:to="loc_idt_IdtPaymentServicesAndIdtFinancialServicesLtdMember_8" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_CommitmentsAndContingenciesTextualAbstract" xlink:label="loc_idt_CommitmentsAndContingenciesTextualAbstract_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_0" xlink:to="loc_idt_CommitmentsAndContingenciesTextualAbstract_9" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PurchaseObligation" xlink:label="loc_us-gaap_PurchaseObligation_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_CommitmentsAndContingenciesTextualAbstract_9" xlink:to="loc_us-gaap_PurchaseObligation_10" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_CommitmentsAndContingenciesTextualAbstract_9" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_11" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_LettersOfCreditExpirationDate" xlink:label="loc_idt_LettersOfCreditExpirationDate_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_CommitmentsAndContingenciesTextualAbstract_9" xlink:to="loc_idt_LettersOfCreditExpirationDate_12" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_PerformanceBondsOutstanding" xlink:label="loc_idt_PerformanceBondsOutstanding_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_CommitmentsAndContingenciesTextualAbstract_9" xlink:to="loc_idt_PerformanceBondsOutstanding_13" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CustomerDepositsCurrent" xlink:label="loc_us-gaap_CustomerDepositsCurrent_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_CommitmentsAndContingenciesTextualAbstract_9" xlink:to="loc_us-gaap_CustomerDepositsCurrent_14" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_CashAndCashEquivalentsSubstantiallyRestricted" xlink:label="loc_idt_CashAndCashEquivalentsSubstantiallyRestricted_15"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_CommitmentsAndContingenciesTextualAbstract_9" xlink:to="loc_idt_CashAndCashEquivalentsSubstantiallyRestricted_15" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherGeneralExpense" xlink:label="loc_us-gaap_OtherGeneralExpense_16"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_idt_CommitmentsAndContingenciesTextualAbstract_9" xlink:to="loc_us-gaap_OtherGeneralExpense_16" order="60" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.idt.net/role/IncomeTaxesDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxContingencyLineItems" xlink:label="loc_us-gaap_IncomeTaxContingencyLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxContingencyTable" xlink:label="loc_us-gaap_IncomeTaxContingencyTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_0" xlink:to="loc_us-gaap_IncomeTaxContingencyTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_1" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_2" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_2" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="idt-20170131.xsd#idt_ElmionNetherlandsBvMember" xlink:label="loc_idt_ElmionNetherlandsBvMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_3" xlink:to="loc_idt_ElmionNetherlandsBvMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_0" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_5" order="10" use="optional"/>
</definitionLink>
</linkbase>

Top
Filing Submission 0001213900-17-002245   –   Alternative Formats (Word / Rich Text, HTML, Plain Text, et al.)

Copyright © 2024 Fran Finnegan & Company LLC – All Rights Reserved.
AboutPrivacyRedactionsHelp — Tue., Apr. 30, 12:44:24.1pm ET