EXHIBIT 5.1
                               October 30, 2000


IDT Corporation
520 Broad Street
Newark, New Jersey 07102

     Re:  IDT Corporation--Registration Statement on Form S-8
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Dear Ladies and Gentlemen:

     I am the Secretary and General Counsel of IDT Corporation (the "Company"),
and as such I have been asked to render the following opinion in connection with
the Registration Statement on Form S-8 to be filed with the Securities and
Exchange Commission (the "SEC") in connection with the registration under the
Securities Act of 1933, as amended, of an aggregate of 1,500,000 shares of the
Company's common stock, par value $.01 (the "Shares"), which will be issuable
under the Company's 1996 Stock Option and Incentive Plan, as Amended and
Restated (the "Plan").

     As your counsel in connection with the Registration Statement, I have
examined the proceedings taken by you in connection with the adoption of the
Plan and the authorization of the issuance of the Shares and such other
documents as I have deemed necessary to render this opinion.

     Based upon the foregoing, it is my opinion that the Shares, when issued and
sold pursuant to the terms of the Plan, will be validly issued, fully paid and
nonassessable shares of Common Stock.

     I consent to the filing of this Opinion as an exhibit to the Registration
Statement.

                                 Very truly yours,


                                 /s/ Joyce J. Mason
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                                 Joyce J. Mason
                                 Secretary and General Counsel

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