<TABLE> <S> <C>
<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM IDT'S FISCAL
1999 FINANCIAL STATEMENTS, AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE
TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<S> <C>
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> JUL-31-1999
<PERIOD-START> AUG-01-1998
<PERIOD-END> JUL-31-1999
<CASH> 52,903,479
<SECURITIES> 77,869,655
<RECEIVABLES> 113,789,127
<ALLOWANCES> 7,643,000
<INVENTORY> 0
<CURRENT-ASSETS> 292,198,280
<PP&E> 151,472,278
<DEPRECIATION> 37,349,355
<TOTAL-ASSETS> 559,871,379
<CURRENT-LIABILITIES> 112,783,537
<BONDS> 0
0
0
<COMMON> 239,829
<OTHER-SE> 276,089,334
<TOTAL-LIABILITY-AND-EQUITY> 559,871,379
<SALES> 732,183,855
<TOTAL-REVENUES> 732,183,855
<CGS> 575,049,683
<TOTAL-COSTS> 739,909,384
<OTHER-EXPENSES> 0
<LOSS-PROVISION> 5,558,000
<INTEREST-EXPENSE> 11,318,964
<INCOME-PRETAX> (10,989,311)
<INCOME-TAX> 7,253,000
<INCOME-CONTINUING> (14,933,759)
<DISCONTINUED> 0
<EXTRAORDINARY> (3,269,787)
<CHANGES> 0
<NET-INCOME> (18,203,546)
<EPS-BASIC> 0
<EPS-DILUTED> (1.33)
</TABLE>