iBASIS, INC. STOCK OPTION AGREEMENT?INCORPORATED TERMS AND CONDITIONS

Exhibit 10.2

        Option No.             

iBASIS, INC.
Stock Option Grant Notice
Stock Option Grant under the Company's
2007 Stock Plan

[Insert Vesting Schedule]

        The Company and the Participant acknowledge receipt of this Stock Option Grant Notice and agree to the terms of the Stock Option Agreement attached hereto and incorporated by reference herein, the Company's 2007 Stock Plan and the terms of this Option Grant as set forth above.

iBASIS, INC.
STOCK OPTION AGREEMENT—INCORPORATED TERMS AND CONDITIONS

        AGREEMENT made as of the date of grant set forth in the Stock Option Grant Notice between iBasis, Inc. (the "Company"), a Delaware corporation, and                         (the "Participant").

        WHEREAS, the Company desires to grant to the Participant an Option to purchase shares of its common stock, $0.001 par value per share (the "Shares"), under and for the purposes set forth in the Company's 2007 Stock Plan (the "Plan");

        WHEREAS, the Company and the Participant understand and agree that any terms used and not defined herein have the same meanings as in the Plan; and

        WHEREAS, the Company and the Participant each intend that the Option granted herein shall be of the type set forth in the Stock Option Grant Notice.

        NOW, THEREFORE, in consideration of the mutual covenants hereinafter set forth and for other good and valuable consideration, the parties hereto agree as follows:

• 1. GRANT OF OPTION.

        The Company hereby grants to the Participant the right and option to purchase all or any part of an aggregate of the number of shares set forth in the Stock Option Grant Notice, on the terms and conditions and subject to all the limitations set forth herein, under United States securities and tax laws, and in the Plan, which is incorporated herein by reference. The Participant acknowledges receipt of a copy of the Plan.

• 2. EXERCISE PRICE.

        The exercise price of the Shares covered by the Option shall be the amount per Share set forth in the Stock Option Grant Notice, subject to adjustment, as provided in the Plan, in the event of a stock split, reverse stock split or other events affecting the holders of Shares after the date hereof (the "Exercise Price"). Payment shall be made in accordance with Paragraph 9 of the Plan.

• 3. EXERCISABILITY OF OPTION.

        Subject to the terms and conditions set forth in this Agreement and the Plan, the Option granted hereby shall become exercisable as set forth in the Stock Option Grant Notice which rights are cumulative and are subject to the other terms and conditions of this Agreement and the Plan.

• 4. TERM OF OPTION.

        This Option shall terminate ten years from the date of this Agreement or, if this Option is designated in the Stock Option Grant Notice as an ISO and the Participant owns as of the date hereof more than 10% of the total combined voting power of all classes of capital stock of the Company or an Affiliate, five years from the date of this Agreement, but shall be subject to earlier termination as provided herein or in the Plan.

        If the Participant ceases to be an employee, director or consultant of the Company or of an Affiliate for any reason other than the death or Disability of the Participant, or termination of the Participant for Cause, the Option may be exercised, if it has not previously terminated, within three months after the date the Participant ceases to provide service to the Company or an Affiliate, or within the originally prescribed term of the Option, whichever is earlier, but may not be exercised thereafter except as set forth below. In such event, the Option shall be exercisable only to the extent that the Option has become exercisable and is in effect at the date of such cessation of service .

2

        If this Option is designated in the Stock Option Grant Notice as an ISO and the Participant ceases to be an employee of the Company or of an Affiliate but continues after termination of employment to provide service to the Company or an Affiliate as a consultant, this Option shall continue to vest in accordance with Section 3 above as if this Option had not terminated until the Participant is no longer providing services to the Company. In such case, this Option shall automatically convert and be deemed a Non-Qualified Option as of the date that is three months from termination of the Participant's employment and this Option shall continue on the same terms and conditions set forth herein until such Participant is no longer providing service to the Company or an Affiliate.

        Notwithstanding the foregoing, in the event of the Participant's Disability or death within three months after the termination of service, the Participant or the Participant's Survivors may exercise the Option within one year after the date of the Participant's termination of service, but in no event after the date of expiration of the term of the Option.

        In the event the Participant's service is terminated by the Company or an Affiliate for Cause, the Participant's right to exercise any unexercised portion of this Option shall, unless otherwise determined by the Board of Directors, cease immediately as of the time the Participant is notified his or her service is terminated for Cause, and this Option shall thereupon terminate. Notwithstanding anything herein to the contrary, if subsequent to the Participant's termination, but prior to the exercise of the Option, the Board of Directors of the Company determines that, either prior or subsequent to the Participant's termination, the Participant engaged in conduct which would constitute Cause, then the Participant shall immediately cease to have any right to exercise the Option and this Option shall thereupon terminate.

        In the event of the Disability of the Participant, as determined in accordance with the Plan, the Option shall be exercisable within one year after the Participant's termination of service or, if earlier, within the term originally prescribed by the Option. In such event, the Option shall be exercisable:

• (a)

  to the extent that the Option has become exercisable but has not been exercised as of the date of Disability; and
  
  

  (b)

  in the event rights to exercise the Option accrue periodically, to the extent of a pro rata portion through the date of Disability of any additional vesting rights that would have accrued on the next vesting date had the Participant not become Disabled. The proration shall be based upon the number of days accrued in the current vesting period prior to the date of Disability.

        In the event of the death of the Participant while an employee, director or consultant of the Company or of an Affiliate, the Option shall be exercisable by the Participant's Survivors within one year after the date of death of the Participant or, if earlier, within the originally prescribed term of the Option. In such event, the Option shall be exercisable:

• (x)

  to the extent that the Option has become exercisable but has not been exercised as of the date of death; and
  
  

  (y)

  in the event rights to exercise the Option accrue periodically, to the extent of a pro rata portion through the date of death of any additional vesting rights that would have accrued on the next vesting date had the Participant not died. The proration shall be based upon the number of days accrued in the current vesting period prior to the Participant's date of death.

        The Participant acknowledges and agrees that neither the Company, its shareholders nor its directors and officers, has any duty or obligation to disclose to the Participant any material information regarding the business of the Company or affecting the value of the Shares before, at the time of, or following a termination of the employment of the Participant by the Company, including, without

3

limitation, any information concerning plans for the Company to make a public offering of its securities or to be acquired by or merged with or into another firm or entity.

• 5. METHOD OF EXERCISING OPTION.

        Subject to the terms and conditions of this Agreement, the Option may be exercised by written notice to the Company or its designee, in substantially the form of Exhibit A attached hereto or by such other form or manner as may be prescribed by the Company or its designee from time to time. Such notice shall state the number of Shares with respect to which the Option is being exercised and shall be signed by the person exercising the Option. Payment of the Exercise Price for such Shares shall be made in accordance with Paragraph 9 of the Plan. The Company shall deliver such Shares as soon as practicable after the notice shall be received, provided, however, that the Company may delay issuance of such Shares until completion of any action or obtaining of any consent, which the Company deems necessary under any applicable law (including, without limitation, state securities or "blue sky" laws). The Shares as to which the Option shall have been so exercised shall be registered in the Company's share register in the name of the person so exercising the Option (or, if the Option shall be exercised by the Participant and if the Participant shall so request in the notice exercising the Option, shall be registered in the Company's share register in the name of the Participant and another person jointly, with right of survivorship) and shall be delivered as provided above to or upon the written order of the person exercising the Option. In the event the Option shall be exercised, pursuant to Section 4 hereof, by any person other than the Participant, such notice shall be accompanied by appropriate proof of the right of such person to exercise the Option. All Shares that shall be purchased upon the exercise of the Option as provided herein shall be fully paid and nonassessable.

• 6. PARTIAL EXERCISE.

        Exercise of this Option to the extent above stated may be made in part at any time and from time to time within the above limits, except that no fractional share shall be issued pursuant to this Option.

• 7. NON-ASSIGNABILITY.

        The Option shall not be transferable