
<PAGE>
                                                                    EXHIBIT 99.2
 
                       NOTICE OF GUARANTEED DELIVERY FOR
 
                                IDT CORPORATION
 
                                WITH RESPECT TO
                          8 3/4% SENIOR NOTES DUE 2006
                             ---------------------
 
            PURSUANT TO THE PROSPECTUS DATED                 , 1998
                             ---------------------
 
    This form or one substantially equivalent hereto must be used by a holder of
the 8 3/4% Senior Notes due 2006 (the "Old Notes") of IDT Corporation, a
Delaware corporation (the "Company"), to accept the Company's Exchange Offer
made pursuant to the Prospectus, dated                , 1998 (the "Prospectus"),
and the related Letter of Transmittal (the "Letter of Transmittal") if
certificates for the Old Notes are not immediately available or if the procedure
for book-entry transfer cannot be completed on a timely basis or time will not
permit all required documents to reach First Trust National Association (the
"Exchange Agent") prior to 5:00 P.M., New York City time, on the Expiration Date
of the Exchange Offer. This Notice of Guaranteed Delivery may be delivered or
transmitted by facsimile transmission, mail or hand delivery to the Exchange
Agent as set forth below. In addition, in order to utilize the guaranteed
delivery procedure to tender Old Notes pursuant to the Exchange Offer, a
completed, signed and dated Letter of Transmittal (or facsimile thereof) must
also be received by the Exchange Agent prior to 5:00 P.M., New York City time,
on the Expiration Date. Capitalized terms not defined herein have the respective
meanings given to them in the Prospectus or the Letter of Transmittal.
 
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  THE EXCHANGE OFFER WILL EXPIRE AT 5:00 P.M., NEW YORK CITY TIME, ON       ,
     1998, UNLESS THE EXCHANGE OFFER IS EXTENDED (THE "EXPIRATION DATE").
--------------------------------------------------------------------------------
 
                    TO: U.S. BANK TRUST NATIONAL ASSOCIATION
 
<TABLE>
<S>                                            <C>
                  BY MAIL:                             BY HAND OR OVERNIGHT COURIER:
    U.S. Bank Trust National Association           U.S. Bank Trust National Association
            180 East Fifth Street                          180 East Fifth Street
          St. Paul, Minnesota 55101                      St. Paul, Minnesota 55101
    Attn: Specialized Finance Department           Attn: Specialized Finance Department
</TABLE>
 
                 BY FACSIMILE (FOR ELIGIBLE INSTITUTIONS ONLY):
                                 (612) 244-1537
                              Confirm by Telephone
                                 (612) 244-1197
 
    DELIVERY OF THIS INSTRUMENT TO AN ADDRESS, OR TRANSMISSION VIA FACSIMILE,
OTHER THAN AS SET FORTH ABOVE, WILL NOT CONSTITUTE A VALID DELIVERY.
 
    This form is not to be used to guarantee signatures. If a signature on a
Letter of Transmittal is required to be guaranteed by an "Eligible Institution"
under the instructions thereto, such signature guarantee must appear in the
applicable space provided in the signature box on the Letter of Transmittal.
<PAGE>
LADIES AND GENTLEMEN:
 
    The undersigned hereby tender(s) to the Company upon the terms and
conditions set forth in the Prospectus and the related Letter of Transmittal,
receipt of which is hereby acknowledged, the aggregate principal amount of Old
Notes set forth below pursuant to the guaranteed delivery procedures set forth
in the Prospectus and the Letter of Transmittal.
 
    The undersigned hereby tenders the Old Notes listed below:
 
<TABLE>
<CAPTION>
-------------------------------------
                                 DESCRIPTION OF OLD NOTES
-------------------------------------
                                                         AGGREGATE PRINCIPAL AMOUNT OF
 NAME(S) AND ADDRESS(ES) OF HOLDER(S)   CERTIFICATE            OLD NOTES TENDERED
      (PLEASE FILL IN, IF BLANK)        NUMBER(S)*            (IF LESS THAN ALL)**
<S>                                     <C>          <C>
-------------------------------------
-------------------------------------
-------------------------------------
-------------------------------------
-------------------------------------
-------------------------------------
-------------------------------------
       TOTAL PRINCIPAL AMOUNT OF OLD NOTES TENDERED
-------------------------------------
</TABLE>
 
*   Need not be completed by holders tendering Old Notes by book-entry transfer.
 
**  Need not be completed by holders who wish to tender with respect to all Old
    Notes listed. See Instruction 2.
 
    If Old Notes will be delivered by book-entry transfer to The Depository
Trust Company, provide account number. Account Number:
--------------------------------------------------------------------------------
 
                                PLEASE SIGN HERE
 
<TABLE>
<S>                                            <C>
X                                              Date:
X                                              Date:
</TABLE>
 
SIGNATURE(S) OF OWNER OR AUTHORIZED SIGNATORY
 
    This Notice of Guaranteed Delivery must be signed by the holder(s) of Old
Notes exactly as the name(s) of the holder(s) appear(s) on the certificate(s)
for the Old Notes or by any person(s) authorized to become (a) holder(s) by
endorsements and documents transmitted herewith. If signature is by a trustee,
 
                                       2
<PAGE>
executor, administrator, guardian, officer or other person acting in a fiduciary
or representative capacity, such person must provide the following information.
 
<TABLE>
<S>                                            <C>
Name(s):                                       Address:
               (PLEASE PRINT)                               (INCLUDE ZIP CODE)
Capacity:                                      Telephone Number:
                                                            (INCLUDE AREA CODE)
</TABLE>
 
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                 THE ACCOMPANYING GUARANTEE MUST BE COMPLETED.
 
                                   GUARANTEE
                    (NOT TO BE USED FOR SIGNATURE GUARANTEE)
 
    The undersigned, a firm that is a member firm of a registered national
securities exchange or of the National Association of Securities Dealers, Inc.,
a commercial bank or trust company having an office correspondent in the United
States or any "eligible guarantor institution" within the meaning of Rule
17Ad-15 of the Securities Exchange Act of 1934, as amended, hereby (a)
represents that each holder of Old Notes on whose behalf this tender is being
made "own(s)" the Old Notes covered hereby within the meaning of Rule 14e-4
under the Securities Exchange Act of 1934, as amended, (b) represents that such
tender of Old Notes complies with Rule 14e-4 and (c) guarantees to deliver to
the Exchange Agent, at its address set forth above, the Old Notes described
above, in proper form for transfer (or confirmation of the book-entry transfer
of such Old Notes into the Exchange Agent's account at The Depository Trust
Company, pursuant to the procedure for book-entry transfer set forth in the
Prospectus), together with a properly completed and duly executed Letter of
Transmittal (or facsimile thereof), any required signature guarantees, and any
other documents required by the Letter of Transmittal by 5:00 p.m., New York
City time, within five New York Stock Exchange trading days following the
Expiration Date.
 
    The undersigned acknowledges that it must deliver the Letter of Transmittal
and Old Notes tendered hereby to the Exchange Agent within the time period set
forth above and that failure to do so could result in financial loss to the
undersigned.
Name of Firm: __________________________________________________________________
By: ____________________________________________________________________________
 
                             (Authorized Signature)
Name: __________________________________________________________________________
Title: _________________________________________________________________________
Address: _______________________________________________________________________
Telephone Number: ______________________________________________________________
 
                              (Include Area Code)
Date: __________________________________________________________________________
 
    DO NOT SEND OLD NOTES WITH THIS FORM, ACTUAL SURRENDER OF OLD NOTES MUST BE
MADE PURSUANT TO, AND BE ACCOMPANIED BY, AN EXECUTED LETTER OF TRANSMITTAL.
 
                                       3
<PAGE>
                                  INSTRUCTIONS
 
1. DELIVERY OF THIS NOTICE OF GUARANTEED DELIVERY.
 
    A properly completed and duly executed copy of this Notice of Guaranteed
Delivery and any other documents required by this Notice of Guaranteed Delivery
must be received by the Exchange Agent at its address set forth herein prior to
the Expiration Date. The method of delivery of this Notice of Guaranteed
Delivery and any other required documents to the Exchange Agent is at the
election and sole risk of the holder, and the delivery will be deemed made only
when actually received by the Exchange Agent. If delivery is by mail, registered
mail with return receipt requested, properly insured, is recommended. As an
alternative to delivery by mail, the holders may wish to consider using an
overnight or hand delivery service. In all cases, sufficient time should be
allowed to assure timely delivery.
 
2. SIGNATURES ON THIS NOTICE OF GUARANTEED DELIVERY.
 
    If this Notice of Guaranteed Delivery is signed by the registered holder(s)
of the Notes referred to herein, the signature must correspond with the name(s)
written on the face of the Notes without alteration, enlargement, or any change
whatsoever. If this Notice of Guaranteed Delivery is signed by a participant of
the Book-Entry Transfer Facility whose name appears on a security position
listing as the owner of the Notes, the signature must correspond with the name
shown on the security position listing as the owner of the Notes.
 
    If this Notice of Guaranteed Delivery is signed by a person other than the
registered holder(s) of any Notes listed or a participant of the Book-Entry
Transfer Facility, this Notice of Guaranteed Delivery must be accompanied by
appropriate bond powers, signed as the name of the registered holder(s) appears
on the Notes or signed as the name of the participant shown on the Book-Entry
Transfer Facility's security position listing.
 
    If this Notice of Guaranteed Delivery is signed by a trustee, executor,
administrator, guardian, attorney-in-fact, officer of a corporation, or other
person acting in a fiduciary or representative capacity, such person should so
indicate when signing and submit with the Letter of Transmittal evidence
satisfactory to the Company of such person's authority to so act.
 
3. REQUESTS FOR ASSISTANCE OR ADDITIONAL COPIES.
 
    Questions and requests for assistance and requests for additional copies of
the Prospectus may be directed to the Exchange Agent at the address specified in
the Prospectus. Holders may also contact their broker, dealer, commercial bank,
trust company, or other nominee for assistance concerning the Exchange Offer.
 
                                       4
