UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                                    FORM 8-K

                                 CURRENT REPORT

     Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

                                   May 4, 2005
                                 ---------------
                Date of Report (Date of earliest event reported)
                                 ---------------

                                  iBASIS, INC.
                                 ---------------
               (Exact Name of Registrant as Specified in Charter)


            DELAWARE                 0-27127                 04-3332534
--------------------------------------------------------------------------------
  (State or Other Jurisdiction     (Commission              (IRS Employer
        of Incorporation)          File Number)           Identification No.)



                     20 Second Avenue, Burlington, MA 01803

            ---------------------------------------------------------
               (Address of Principal Executive Offices) (Zip Code)


                                 (781) 505-7500

              (Registrant's telephone number, including area code)
                                 ---------------


Check the appropriate box below if the Form 8-K filing is intended to
simultaneously satisfy the filing obligation of the registrant under any of the
following provisions:

[ ]  Written communications pursuant to Rule 425 under the Securities Act (17
     CFR 230.425)

[ ]  Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR
     240.14a-12)

[ ]  Pre-commencement communications pursuant to Rule 14d-2(b) under the
     Exchange Act (17 CFR 240.14d-2(b))

[ ]  Pre-commencement communications pursuant to Rule 13e-4(c) under the
     Exchange Act (17 CFR 240.13e-4(c))





Item 2.02. Results of Operations and Financial Condition.

On May 4, 2005, iBasis, Inc. (the "Registrant") issued a press release regarding
its results of operations for the fiscal quarter ended March 31, 2005. A copy of
this press release is being furnished herewith as Exhibit 99.1 and is
incorporated herein by reference.

The information contained herein and in the accompanying exhibit shall not be
incorporated by reference into any filing of the Registrant, whether made before
or after the date hereof, regardless of any general incorporation language in
such filing, unless expressly incorporated by specific reference to such filing.
The information in this report, including the exhibit hereto, is furnished
pursuant to Item 2.02 and shall not be deemed to be "filed" for purposes of
Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise
subject to the liabilities of that section or Sections 11 and 12(a)(2) of the
Securities Act of 1933, as amended.


Item 9.01. Financial Statements and Exhibits.

       (c)   Exhibits.

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

             Exhibit 99.1      Press Release, dated May 4, 2005




                                    SIGNATURE
                                    ---------

     Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

Date: May 4, 2005              iBASIS, INC.

                               By: /s/ Richard Tennant
                                   -------------------------------
                                   Vice President, Finance and Administration
                                   And Chief Financial Officer
                                   (Principal Financial and Accounting Officer)