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                                                                   Exhibit 23.01
 
                        CONSENT OF INDEPENDENT AUDITORS
 
    We consent to the references to our firm under the captions "Selected
Consolidated Financial and Operating Data" and "Experts" and to the use of our
report dated September 25, 1997, in Amendment No. 2 to Registration Statement
No. 333-43501 on Form S-3 and related Prospectus of IDT Corporation for the
registration of 4,815,000 shares of its common stock.
 
                                            /s/ Ernst & Young LLP
                                            ERNST & YOUNG LLP
 
New York, New York
January 23, 1998
