<PAGE>

    As filed with the Securities and Exchange Commission on December 9, 2002
                             Registration No. 333-
         --------------------------------------------------------------
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                            ------------------------
                                    FORM S-8
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                            ------------------------
                                NET2PHONE, INC.
             (Exact Name of Registrant as Specified in its Charter)

             Delaware                               22-3559037
     (State of Incorporation)          (I.R.S. Employer Identification No.)

                                520 Broad Street
                            Newark, New Jersey 07102
               (Address of Principal Executive Offices)(Zip Code)
                            ------------------------

                          Net2Phone, Inc. 401(k) Plan
                            (Full Title of the Plan)
                            ------------------------
                              Stephen M. Greenberg
                    Net2Phone, Inc., Chief Executive Officer
                   520 Broad Street, Newark, New Jersey 07102
                                 (973) 438-3111
(Name, address and telephone number, including area code, of agent for service)
                            ------------------------
                                    Copy to:
                            Richard W. Porter, P.C.
                                Kirkland & Ellis
                    200 E. Randolph Drive, Chicago, IL 60601
                                 (312) 861-2000

                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
-------------------------------------------------------------------------------------------------------
                                             Proposed Maximum       Amount of
Title of Securities    Amount to be          Offering Price         Aggregate Offering     Registration
to be Registered       Registered (1)        Per Share (2)          Price (2)              Fee
-------------------------------------------------------------------------------------------------------
<S>                   <C>                   <C>                    <C>                   <C>
Common Stock,          600,000               $3.90                  $2,340,000            $216.00
$0.01 par value
-------------------------------------------------------------------------------------------------------
</TABLE>

(1) In the event of a stock split, stock dividend, or similar transaction
involving the Registrant's common stock, in order to prevent dilution, the
number of shares registered shall be automatically increased to cover the
additional shares in accordance with Rule 416(a) under the Securities Act of
1933, as amended (the "Securities Act").

(2) Estimated solely for the purpose of calculating the amount of the
registration fee, pursuant to Rules 457(c) and 457(h) of the Securities Act, on
the basis of the average high and low prices of the Registrant's common stock on
December 5, 2002.

         --------------------------------------------------------------
         --------------------------------------------------------------

<PAGE>

                                     PART I
              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1.  Plan Information

    The documents containing the information specified in Item 1 of Part I will
be delivered to participants in the plan covered by this registration statement,
in accordance with Form S-8 and Rule 428 under the Securities Act of 1933, as
amended (the "Securities Act"). Such documents are not required to be, and are
not, filed with the Securities and Exchange Commission ("Commission") either as
part of this registration statement or as prospectuses or prospectus supplements
pursuant to Rule 424. These documents and the documents incorporated by
reference into this registration statement pursuant to Item 3 of Part II of this
registration statement, taken together, constitute a prospectus that meets the
requirements of Section 10(a) of the Securities Act.

Item 2.  Registrant Information and Employee Plan Annual Information.

    Upon written or oral request, any of the documents incorporated by reference
in Item 3 of Part II of this registration statement (which documents are
incorporated by reference in the Section 10(a) prospectus), other documents
required to be delivered to eligible employees pursuant to Rule 428(b) or
additional information about the Net2Phone, Inc. 401(k) Plan are available
without charge by contacting:

                           Human Resources Department
                                Net2Phone, Inc.
                                520 Broad Street
                            Newark, New Jersey 07102
                                 (973) 438-3111

                                    PART II
               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference.

    The Commission allows us to incorporate by reference the information we file
with them, which means that we can disclose important information to you by
referring you to those documents. The information incorporated by reference is
an important part of this registration statement, and information that we file
later with the Commission will automatically update and supersede this
information. We incorporate by reference the documents listed below and any
future filings made with the Commission under Sections 13(a), 13(c), 14, or
15(d) of the Securities and Exchange Act of 1934, as amended (the "Exchange
Act"), until such time as this registration statement is no longer in effect:

            (a) Our Annual Report on Form 10-K for the fiscal year ended July
31, 2002;

            (b) The description of our common stock contained in our
Registration Statement on Form 8-A filed with the Commission on July 20,1999,
including any amendment or report filed for the purpose of updating such
description.

Item 4.  Description of Securities.

    Not applicable.

<PAGE>

Item 5.  Interests of Named Experts and Counsel.

    Bruce D. Shoulson, who has rendered an opinion as to the validity of the
common stock being registered by this registration statement, is an employee of
Net2Phone, Inc.

Item 6.  Indemnification of Directors and Officers.

     Reference is made to Section 145 of the Delaware General Corporation Law
which allows for the indemnification of officers, directors, and other corporate
agents in terms sufficiently broad to indemnify such persons under certain
circumstances for liabilities (including reimbursement for expenses incurred)
arising under the Securities Act, and to Section 102(6)(7) of the Delaware
General Corporation Law, which provides for the elimination or limitation of the
personal liability for monetary damages of directors under certain
circumstances. Article Sixth of our Certificate of Incorporation and Article
VIII of our Bylaws provide for indemnification of our directors, officers,
employees and other agents to the extent and under the circumstances permitted
by the Delaware General Corporation Law.

Item 7.  Exemption from Registration Claimed.

    Not applicable.

Item 8.  Exhibits.

Exhibit
Number      Description
-------     -----------

5.1         Opinion of Bruce D. Shoulson, General Counsel of Net2Phone, Inc.

23.1        Consent of Bruce D. Shoulson (included in Exhibit 5.1)

23.2        Consent of Ernst & Young LLP, Independent Auditors

24.1        Power of Attorney (included in signature page)


Item 9. Undertakings.

    The undersigned Registrant hereby undertakes:

         (1) to file, during any period in which offers or sales are being made,
         a post-effective amendment to this registration statement to include
         any material information with respect to the plan of distribution not
         previously disclosed in the registration statement or any material
         change to such information in the registration statement.

         (2) that, for purposes of determining any liability under the
         Securities Act, each such post-effective amendment shall be deemed to
         be a new registration statement relating to the securities offered
         therein, and the offering of such securities at that time shall be
         deemed to be the initial bona fide offering thereof.

         (3) to remove from registration by means of a post-effective amendment
         any of the securities being registered which remain unsold at the
         termination of the offering.

     The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Exchange Act that is incorporated by reference in the registration statement
shall be deemed to be a new registration statement relating to the securities
offered therein, and the offering of such securities at that time shall be
deemed to be the initial bona fide offering thereof.

<PAGE>

     Insofar as the indemnification for liabilities arising under the Securities
Act may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the Commission such indemnification is
against public policy as expressed in the Securities Act and is, therefore,
unenforceable. In the event that a claim for indemnification against such
liabilities (other than the payment by the Registrant of expenses incurred or
paid by a director, officer or controlling person of the Registrant in a
successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered hereunder, the Registrant will, unless in the opinion of its counsel
the question has already been settled by controlling precedent, submit to a
court of appropriate jurisdiction the question of whether such indemnification
by it is against public policy as expressed in the Securities Act and will be
governed by the final adjudication of such issue.


<PAGE>

                                   SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this registration
statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Newark, State of New Jersey, on this 9th day of
December, 2002.

                                             NET2PHONE, INC.

                                             /s/  Stephen M. Greenberg
                                             -----------------------------------
                                             Stephen M. Greenberg
                                             Chief Executive Officer


                               POWER OF ATTORNEY

     KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Stephen M. Greenberg and Bruce D.
Shoulson, jointly and severally, his attorneys-in-fact and agents, each with the
power of substitution and resubstitution, for him or her and in his name, place
or stead, in any and all capacities, to sign any amendments to this Registration
Statement on Form S-8, and to file such amendments, together with exhibits and
other documents in connection therewith, with the Securities and Exchange
Commission, granting to each attorney-in-fact and agent, full power and
authority to do and perform each and every act and thing requisite and necessary
to be done in and about the premises, as fully as he or she might or could do in
person, and ratifying and confirming all that the attorney-in-facts and agents,
or his substitute or substitutes, may do or cause to be done by virtue hereof.

     Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed by the following persons in the
capacities and on the dates indicated.

<TABLE>
<CAPTION>
Signature                                             Title                          Date
-----------------------------------------------------------------------------------------------
<S>                                         <C>                               <C>
/s/ Stephen M. Greenberg
---------------------------                  Chief Executive Officer           December 9, 2002
Stephen M. Greenberg                         (Principal Executive
                                             Officer) and Director

/s/ Arthur Dubroff
---------------------------                  Chief Financial Officer           December 9, 2002
Arthur Dubroff                               (Principal Accounting and
                                             Financial Officer)

/s/ Howard S. Jonas
---------------------------                  Chairman of the Board             December 9, 2002
Howard S. Jonas                              and Director


/s/ James A. Courter
---------------------------                  Director                          December 9, 2002
James A. Courter


---------------------------                  Director                          December 9, 2002
Michael Fischberger
</TABLE>

<PAGE>

<TABLE>
<CAPTION>
Signature                                             Title                          Date
-----------------------------------------------------------------------------------------------
<S>                                         <C>                               <C>
/s/ Harry C. McPherson
---------------------------                  Director                          December 9, 2002
Harry C. McPherson, Jr.

/s/ James R. Mellor
---------------------------                  Director                          December 9, 2002
James R. Mellor

/s/ Stephen Goldsmith
---------------------------                  Director                          December 9, 2002
Stephen Goldsmith

/s/ Daniel H. Schulman
---------------------------                  Director                          December 9, 2002
Daniel H. Schulman

/s/ Joyce J. Mason                           Director                          December 9, 2002
---------------------------
Joyce J. Mason

/s/ Stephen R. Brown                         Director                          December 9, 2002
---------------------------
Stephen R. Brown

/s/ Anthony G. Werner                        Director                          December 9, 2002
---------------------------
Anthony G. Werner

/s/ Jesse P. King                            Director                          December 9, 2002
---------------------------
Jesse P. King

/s/ Michael J. Weiss
---------------------------                  Director                          December 9, 2002
Michael J. Weiss
</TABLE>

<PAGE>

                               INDEX TO EXHIBITS

Exhibit
Number      Description
-------     -----------

5.1         Opinion of Bruce D. Shoulson, General Counsel of Net2Phone, Inc.

23.1        Consent of Bruce D. Shoulson (included in Exhibit 5.1)

23.2        Consent of Ernst & Young LLP, Independent Auditors

24.1        Power of Attorney (included in signature page)
[{"type": "S-8", "sequence": "1", "filename": "b321704_s8.txt", "description": "FORM S-8", "secsgml_size_bytes": 15673}]
{"company-data": {"conformed-name": "NET2PHONE INC", "cik": "0001086472", "assigned-sic": "4813", "irs-number": "223559037", "state-of-incorporation": "DE", "fiscal-year-end": "0731"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-101734", "film-number": "02852724"}, "business-address": {"street1": "520 BROAD STREET", "city": "NEWARK", "state": "NJ", "zip": "07102", "phone": "9734122800"}, "mail-address": {"street1": "17 MAIN STREET", "city": "HACKENSACK", "state": "NJ", "zip": "07601"}}
As filed with the Securities and Exchange Commission on December 9, 2002
                             Registration No. 333-
         --------------------------------------------------------------
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                            ------------------------
                                    FORM S-8
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                            ------------------------
                                NET2PHONE, INC.
             (Exact Name of Registrant as Specified in its Charter)

             Delaware                               22-3559037
     (State of Incorporation)          (I.R.S. Employer Identification No.)

                                520 Broad Street
                            Newark, New Jersey 07102
               (Address of Principal Executive Offices)(Zip Code)
                            ------------------------

                          Net2Phone, Inc. 401(k) Plan
                            (Full Title of the Plan)
                            ------------------------
                              Stephen M. Greenberg
                    Net2Phone, Inc., Chief Executive Officer
                   520 Broad Street, Newark, New Jersey 07102
                                 (973) 438-3111
(Name, address and telephone number, including area code, of agent for service)
                            ------------------------
                                    Copy to:
                            Richard W. Porter, P.C.
                                Kirkland & Ellis
                    200 E. Randolph Drive, Chicago, IL 60601
                                 (312) 861-2000

                        CALCULATION OF REGISTRATION FEE
-------------------------------------------------------------------------------------------------------
                                             Proposed Maximum       Amount of
Title of Securities    Amount to be          Offering Price         Aggregate Offering     Registration
to be Registered       Registered (1)        Per Share (2)          Price (2)              Fee
-------------------------------------------------------------------------------------------------------
Common Stock,          600,000               $3.90                  $2,340,000            $216.00
$0.01 par value
-------------------------------------------------------------------------------------------------------
(1) In the event of a stock split, stock dividend, or similar transaction
involving the Registrant's common stock, in order to prevent dilution, the
number of shares registered shall be automatically increased to cover the
additional shares in accordance with Rule 416(a) under the Securities Act of
1933, as amended (the "Securities Act").

(2) Estimated solely for the purpose of calculating the amount of the
registration fee, pursuant to Rules 457(c) and 457(h) of the Securities Act, on
the basis of the average high and low prices of the Registrant's common stock on
December 5, 2002.

         --------------------------------------------------------------
         --------------------------------------------------------------
PART I
              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1.  Plan Information

    The documents containing the information specified in Item 1 of Part I will
be delivered to participants in the plan covered by this registration statement,
in accordance with Form S-8 and Rule 428 under the Securities Act of 1933, as
amended (the "Securities Act"). Such documents are not required to be, and are
not, filed with the Securities and Exchange Commission ("Commission") either as
part of this registration statement or as prospectuses or prospectus supplements
pursuant to Rule 424. These documents and the documents incorporated by
reference into this registration statement pursuant to Item 3 of Part II of this
registration statement, taken together, constitute a prospectus that meets the
requirements of Section 10(a) of the Securities Act.

Item 2.  Registrant Information and Employee Plan Annual Information.

    Upon written or oral request, any of the documents incorporated by reference
in Item 3 of Part II of this registration statement (which documents are
incorporated by reference in the Section 10(a) prospectus), other documents
required to be delivered to eligible employees pursuant to Rule 428(b) or
additional information about the Net2Phone, Inc. 401(k) Plan are available
without charge by contacting:

                           Human Resources Department
                                Net2Phone, Inc.
                                520 Broad Street
                            Newark, New Jersey 07102
                                 (973) 438-3111

                                    PART II
               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference.

    The Commission allows us to incorporate by reference the information we file
with them, which means that we can disclose important information to you by
referring you to those documents. The information incorporated by reference is
an important part of this registration statement, and information that we file
later with the Commission will automatically update and supersede this
information. We incorporate by reference the documents listed below and any
future filings made with the Commission under Sections 13(a), 13(c), 14, or
15(d) of the Securities and Exchange Act of 1934, as amended (the "Exchange
Act"), until such time as this registration statement is no longer in effect:

            (a) Our Annual Report on Form 10-K for the fiscal year ended July
31, 2002;

            (b) The description of our common stock contained in our
Registration Statement on Form 8-A filed with the Commission on July 20,1999,
including any amendment or report filed for the purpose of updating such
description.

Item 4.  Description of Securities.

    Not applicable.
Item 5.  Interests of Named Experts and Counsel.

    Bruce D. Shoulson, who has rendered an opinion as to the validity of the
common stock being registered by this registration statement, is an employee of
Net2Phone, Inc.

Item 6.  Indemnification of Directors and Officers.

     Reference is made to Section 145 of the Delaware General Corporation Law
which allows for the indemnification of officers, directors, and other corporate
agents in terms sufficiently broad to indemnify such persons under certain
circumstances for liabilities (including reimbursement for expenses incurred)
arising under the Securities Act, and to Section 102(6)(7) of the Delaware
General Corporation Law, which provides for the elimination or limitation of the
personal liability for monetary damages of directors under certain
circumstances. Article Sixth of our Certificate of Incorporation and Article
VIII of our Bylaws provide for indemnification of our directors, officers,
employees and other agents to the extent and under the circumstances permitted
by the Delaware General Corporation Law.

Item 7.  Exemption from Registration Claimed.

    Not applicable.

Item 8.  Exhibits.

Exhibit
Number      Description
-------     -----------

5.1         Opinion of Bruce D. Shoulson, General Counsel of Net2Phone, Inc.

23.1        Consent of Bruce D. Shoulson (included in Exhibit 5.1)

23.2        Consent of Ernst & Young LLP, Independent Auditors

24.1        Power of Attorney (included in signature page)

Item 9. Undertakings.

    The undersigned Registrant hereby undertakes:

         (1) to file, during any period in which offers or sales are being made,
         a post-effective amendment to this registration statement to include
         any material information with respect to the plan of distribution not
         previously disclosed in the registration statement or any material
         change to such information in the registration statement.

         (2) that, for purposes of determining any liability under the
         Securities Act, each such post-effective amendment shall be deemed to
         be a new registration statement relating to the securities offered
         therein, and the offering of such securities at that time shall be
         deemed to be the initial bona fide offering thereof.

         (3) to remove from registration by means of a post-effective amendment
         any of the securities being registered which remain unsold at the
         termination of the offering.

     The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Exchange Act that is incorporated by reference in the registration statement
shall be deemed to be a new registration statement relating to the securities
offered therein, and the offering of such securities at that time shall be
deemed to be the initial bona fide offering thereof.
Insofar as the indemnification for liabilities arising under the Securities
Act may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the Commission such indemnification is
against public policy as expressed in the Securities Act and is, therefore,
unenforceable. In the event that a claim for indemnification against such
liabilities (other than the payment by the Registrant of expenses incurred or
paid by a director, officer or controlling person of the Registrant in a
successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered hereunder, the Registrant will, unless in the opinion of its counsel
the question has already been settled by controlling precedent, submit to a
court of appropriate jurisdiction the question of whether such indemnification
by it is against public policy as expressed in the Securities Act and will be
governed by the final adjudication of such issue.
SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this registration
statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Newark, State of New Jersey, on this 9th day of
December, 2002.

                                             NET2PHONE, INC.

                                             /s/  Stephen M. Greenberg
                                             -----------------------------------
                                             Stephen M. Greenberg
                                             Chief Executive Officer

                               POWER OF ATTORNEY

     KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Stephen M. Greenberg and Bruce D.
Shoulson, jointly and severally, his attorneys-in-fact and agents, each with the
power of substitution and resubstitution, for him or her and in his name, place
or stead, in any and all capacities, to sign any amendments to this Registration
Statement on Form S-8, and to file such amendments, together with exhibits and
other documents in connection therewith, with the Securities and Exchange
Commission, granting to each attorney-in-fact and agent, full power and
authority to do and perform each and every act and thing requisite and necessary
to be done in and about the premises, as fully as he or she might or could do in
person, and ratifying and confirming all that the attorney-in-facts and agents,
or his substitute or substitutes, may do or cause to be done by virtue hereof.

     Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed by the following persons in the
capacities and on the dates indicated.
Signature                                             Title                          Date
-----------------------------------------------------------------------------------------------
/s/ Stephen M. Greenberg
---------------------------                  Chief Executive Officer           December 9, 2002
Stephen M. Greenberg                         (Principal Executive
                                             Officer) and Director

/s/ Arthur Dubroff
---------------------------                  Chief Financial Officer           December 9, 2002
Arthur Dubroff                               (Principal Accounting and
                                             Financial Officer)

/s/ Howard S. Jonas
---------------------------                  Chairman of the Board             December 9, 2002
Howard S. Jonas                              and Director

/s/ James A. Courter
---------------------------                  Director                          December 9, 2002
James A. Courter

---------------------------                  Director                          December 9, 2002
Michael Fischberger
Signature                                             Title                          Date
-----------------------------------------------------------------------------------------------
/s/ Harry C. McPherson
---------------------------                  Director                          December 9, 2002
Harry C. McPherson, Jr.

/s/ James R. Mellor
---------------------------                  Director                          December 9, 2002
James R. Mellor

/s/ Stephen Goldsmith
---------------------------                  Director                          December 9, 2002
Stephen Goldsmith

/s/ Daniel H. Schulman
---------------------------                  Director                          December 9, 2002
Daniel H. Schulman

/s/ Joyce J. Mason                           Director                          December 9, 2002
---------------------------
Joyce J. Mason

/s/ Stephen R. Brown                         Director                          December 9, 2002
---------------------------
Stephen R. Brown

/s/ Anthony G. Werner                        Director                          December 9, 2002
---------------------------
Anthony G. Werner

/s/ Jesse P. King                            Director                          December 9, 2002
---------------------------
Jesse P. King

/s/ Michael J. Weiss
---------------------------                  Director                          December 9, 2002
Michael J. Weiss
INDEX TO EXHIBITS

Exhibit
Number      Description
-------     -----------

5.1         Opinion of Bruce D. Shoulson, General Counsel of Net2Phone, Inc.

23.1        Consent of Bruce D. Shoulson (included in Exhibit 5.1)

23.2        Consent of Ernst & Young LLP, Independent Auditors

24.1        Power of Attorney (included in signature page)