Employment Agreement - Net2Phone Inc. and Clifford M. Sobel
                                Net2Phone, Inc.
                                171 Main Street
                         Hackensack, New Jersey  07601
                                 May 17, 1999
Clifford M. Sobel
40 Dorrison Drive
Short Hills, New Jersey  07078
Dear Cliff:
     This letter agreement is being entered into in connection with your
agreement to retain your common stock (the "Common Stock") of Net2Phone, Inc.
("Net2Phone"), in lieu of becoming a holder of Net2Phone class A common stock
(the "Class A Stock").
     In consideration of your agreement not to participate in the Net2Phone
recapitalization pursuant to which IDT Corporation ("IDT") became a holder of
Class A Stock, Net2Phone and IDT have agreed to provide you with certain
piggyback registration rights relating to the shares of Common Stock you hold
today and undertaking to ensure that you remain Chairman of Net2Phone for a
period of three years, both as provided herein.
     1.  Net2Phone hereby grants you "piggy-back" registration rights relating
         to the shares of Common Stock you hold today under the same terms and
         conditions as those rights granted to Net2Phone's Series A Preferred
         stockholders as set forth in the Series A Preferred Shareholder
         Registration Rights Agreement, dated as of May 13, 1999, among
         Net2Phone and each of the investors listed on Schedule A thereto (the
         "Agreement"); provided, however, that you agree to be subject to the
         allocation provisions contained in Section 2.7 of the Agreement.
     2.  IDT agrees that upon a Qualifying Public Offering (as defined in the
         Agreement), IDT shall vote its Class A Stock or Common Stock, as the
         case may be, provided that you remain in compliance with the terms of
         your employment agreement, to elect you to that class of directors of
         Net2Phone's staggered board whose term expires three years from the
         date of election.
     3.  If no Qualifying Public Offering occurs, IDT agrees to vote its Class A
         Stock or Common Stock, as the case may be, to re-elect you Chairman of
         the firm at each of the next two annual stockholder meetings.
     4.  To clarify the rights and obligations of the parties, upon the
         occurrence of a Qualifying Public Offering, IDT shall be released from
         any obligations to pay to you any amount of salary or other benefits
         payable pursuant to your employment agreement, as amended, and
         Net2Phone shall be solely obligated as to such payments.
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                                Net2Phone, Inc.
Clifford Sobel
May 17, 1999
Page Two
     Please acknowledge your acceptance to the terms of this letter by executing
below.
                              Very truly yours,
                              /s/ Howard Balter
                              Howard S. Balter
                              Chief Executive Officer
AGREED TO AND ACCEPTED:
/s/ Clifford M. Sobel
--------------------------------------
Clifford M. Sobel
IDT CORPORATION
By: /s/ Joyce Mason
   -----------------------------------
Name: Joyce Mason
Title: General Counsel