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Exhibit 10.57    
    

 
 

JOINDER AGREEMENT    
    

        Reference is hereby made to the Securities Exchange Agreement dated as of February 21, 2003 (the "Exchange
Agreement"), by and between the iBasis, Inc. (the "Company"), iBasis Global, Inc.
("Global" and, together with the Company, the "Borrower"), iBasis Securities Corporation, JMG Triton
Offshore Fund Limited CITCO and the other Exchanging Holders named therein, and U.S. Bank National Association, as Collateral Agent, Fiscal Agent and Warrant Agent (the
"Agent"). Capitalized terms used herein and not otherwise defined shall have the meanings assigned to such terms in the Exchange Agreement. 

        Pursuant
to the terms and conditions of the Exchange Agreement, the Borrower, the Agent and the persons set forth on Annex A hereto (the "Acceding
Holders" and each, individually, an "Acceding Holder") and each person that becomes an Acceding Holder to this Joinder Agreement
pursuant to Section 9 hereof hereby agree as follows: 

        SECTION 1.    Subject to the terms and conditions of this Joinder Agreement, dated as of May 29, 2003 (this
"Joinder Agreement"), each Acceding Holder hereby agrees to exchange, on or as of the Effective Date (as defined below), Convertible Notes in the
aggregate principal amount set forth opposite such Acceding Holder's name on Annex A hereto for (a) the aggregate principal amount set
forth opposite such Acceding Holder's name on Annex A hereto of the Borrower's 11.5% Senior Secured Notes due 2005 and (b) Warrants
exercisable for an aggregate number of shares of Common Stock set forth opposite such Acceding Holder's name on Annex A hereto, all in accordance
with the terms and conditions set forth in the Exchange Agreement. Each Acceding Holder hereby agrees to be bound by, and hereby requests the agreement of the Borrower and the Agent that such Acceding
Holder shall be entitled to the benefits of, all of the terms, conditions and provisions of the Exchange Agreement as if such Acceding Holder had been one of the Persons originally executing the
Exchange Agreement as an "Exchanging Holder"; provided that nothing herein shall be construed as making such Acceding Holder liable to the Borrower or
the other Exchanging Holders or the Borrower liable to such Acceding Holder in respect of any acts or omissions of any party to the Exchange Agreement or in respect of any other event occurring prior
to the Effective Date (as defined below) of this Joinder Agreement. Furthermore, each Acceding Holder expressly acknowledges and agrees that by executing and delivering this Joinder Agreement
(i) it becomes a party to the Exchange Agreement, the Intercreditor Agreement and the Subordination Agreement, in each case as an "Exchanging Holder", (ii) it accepts and shall be
subject to the terms of the Fiscal Agency Agreement and the Warrant Agreement as a Noteholder and
a Warrantholder, respectively, and (iii) it accepts and shall be subject to the terms of each of the Credit Documents as an Exchanging Holder, as the same may be applicable. 

        SECTION 2.    (a) Each Acceding Holder, subject to Section 2(b) below, severally, but not jointly with any other Acceding
Holder, (i) represents and warrants that (A) it is duly and legally authorized to enter into this Joinder Agreement, (B) the execution, delivery and performance of this Joinder
Agreement do not conflict with any provision of law or, if such Acceding Holder is not an individual, of the charter or by-laws of such Acceding Holder, or of any agreement binding on such
Acceding Holder, and (C) all acts, conditions and things required to be done and performed and to have occurred prior to the execution, delivery and performance of this Joinder Agreement, and
to render the same the legal, valid and binding obligation of such Acceding Holder, enforceable against it in accordance with its terms, have been done and performed and have occurred in due and
strict compliance with all applicable laws; (ii) confirms that it has received a copy of the Exchange Agreement, together with such other documents and information as it has deemed appropriate
to make its own credit analysis and decision to enter into this Joinder Agreement; (iii) agrees that it will, independently and without reliance upon the Exchanging Holders or the Agent and
based on such documents and information as it shall deem appropriate at the time, continue to make its own credit decisions in taking or not taking action under the Exchange Agreement;
(iv) appoints and authorizes the Agent to take such action as 

 

agent
on its behalf and to exercise such powers under the Exchange Agreement and the other Loan Documents as are delegated to the Agent by the terms thereof, together with such powers as are
reasonably incidental thereto; and (v) agrees that it will perform in accordance with their terms all of the obligations which by the terms of the Exchange Agreement are required to be
performed by it as an Exchanging Holder. 

        (b)
Each Acceding Holder, severally, but not jointly with any other Acceding Holder, represents and warrants only as to itself that, except as set forth on  Schedule 2 attached hereto, it is an
"accredited investor" as that term is defined in Rule 501 of Regulation D promulgated under
the Securities Act, by virtue, inter alia, of its being (i) a corporation, Massachusetts or similar business trust, or partnership, not formed
for the specific purpose of acquiring the Warrants or the shares of Common Stock issuable upon exercise of the Warrants, with total assets in excess of $5,000,000, (ii) a natural person whose
individual net worth, or joint net worth with that person's spouse, at the time of his or her exchange exceeds $1,000,000, or (iii) a natural person who had an individual income in excess of
$200,000 in each of the two most recent years or joint income with that person's spouse in excess of $300,000 in each of those years and has a reasonable expectation of reaching the same income level
in the current year. The Company hereby waives the accredited investor representation set forth in Section 8.5 of the Exchange Agreement for those Acceding Holders set forth on  Schedule 2.

        SECTION 3.    The Acceding Holders hereby request that the Borrower issue a new global note increasing the principal amount by
$6,100,000 and a new global warrant increasing the number of shares
exercisable thereunder by an aggregate of 1,116,605 shares of Common Stock; and the Company hereby authorizes and directs the Agent to authenticate and register, in the names and denominations
specified herein, and to deliver each such Global Security, when so authenticated and registered, to The Depository Trust Company, or its custodian, on the Effective Date (as defined below). 

        SECTION 4.    The effective date for this Joinder Agreement shall be May 29, 2003 (the "Effective
Date"). Following the execution of this Joinder Agreement by the Borrower and the Acceding Holders, it will be delivered to the Agent for acceptance. 

        SECTION 5.    By execution of this Joinder Agreement, the Borrower hereby certifies that: (i) the sum of the aggregate
original principal amount of the Notes to be issued pursuant to this Joinder Agreement, together with the aggregate original principal amount of all other Notes previously issued under the Fiscal
Agency Agreement, does not exceed $28,750,000; (ii) the sum of the aggregate amount of Warrant Shares issuable upon exercise of the Warrants to be issued pursuant to this Joinder Agreement,
together with the aggregate amount of Warrant Shares issuable (or, if exercised, issued) upon exercise of all Warrants previously issued pursuant to any and all other Joinder Agreements entered into
pursuant to (and after the date of) the Exchange Agreement (which, for avoidance of doubt, does not include any Warrants issued to the Exchanger, as that term is defined in and pursuant to the
Exchange Agreement, or any Warrants issued pursuant to the Symphony Exchange Agreement) does not exceed 1,967,798; and (iii) this Joinder Agreement, and the Notes and Warrants to be issued
pursuant thereto, constitutes a Permitted Exchange in accordance with Section 9.3 of, and otherwise is in accordance with, the Exchange Agreement. 

        SECTION 6.    THIS JOINDER AGREEMENT SHALL FOR ALL PURPOSES BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE
WITH, THE LAWS OF THE COMMONWEALTH OF MASSACHUSETTS (WITHOUT REGARD TO THE PRINCIPLES OF CONFLICTS OF LAWS).

        SECTION 7.    The use in this Joinder Agreement of neuter pronouns in reference to a party hereto shall be deemed to include the
masculine or feminine, as the context may require. 

        SECTION 8.    This Joinder Agreement may be executed in any number of counterparts which shall together constitute but one and
the same agreement. This Joinder Agreement, once duly executed 

2

 

and
delivered in accordance with the terms of the Exchange Agreement, may be relied upon conclusively by the Agent. 

        SECTION 9.    Any person that is a holder of Convertible Notes may become an Acceding Holder party to this Joinder Agreement by
executing and delivering to the Borrower and the Agent, on or prior to June 30, 2003, an Instrument of Accession, substantially in the form of Annex
B attached hereto,
provided that the Borrower and the Agent consent to such person becoming an Acceding Holder party to this Joinder Agreement (which consent shall be conclusively deemed to have been given by the
Borrower and Agent when each countersigns the Instrument of Accession executed by such person). Any such Instrument of Accession executed by any such person and countersigned by the Borrower and Agent
shall become a part of this Joinder Agreement. It is hereby understood and agreed that each of Annex A and  Schedule 2 shall be updated to reflect
such Acceding Holder's interest. Any exchange of Convertible Notes for Notes by a holder of Convertible
Notes who becomes an Acceding Party to this Joinder Agreement shall be deemed to have occurred for all purposes of this Joinder Agreement and such Convertible Notes as of the Effective Date,
regardless of the date on which exchange may actually be consummated. 

[Remainder
of Page Intentionally Left Blank] 

3

        IN WITNESS WHEREOF, intending to be legally bound, each of the undersigned has caused this Joinder Agreement to be executed on its behalf
by its officer thereunto duly authorized, to take effect as a sealed instrument as of the date first above written. 

	 	 	iBASIS, INC.
	

 	
 	

By:	

/s/  OFER GNEEZY      
 Name:  Ofer Gneezy

Title:    President and CEO
	
 	
 	

iBASIS GLOBAL, INC.
	

 	
 	

By:	

/s/  RICHARD TENNANT      
 Name:  Richard Tennant

Title:    Treasurer & CFO

	
 	
 	
ACCEDING HOLDERS

listed on Annex A hereto
	

 	
 	
By:	
 	

COMMONWEALTH ADVISORS, INC.

their attorney in fact
	

 	
 	

 	
 	

By	

/s/  WALTER MORALES      
 Name:      Walter Morales

Title:        President

Address:  P.O. Box 3395

                 Baton Rouge, LA 70821

	Acknowledged this 29 day of May, 2003:	 
	
U.S. BANK NATIONAL ASSOCIATION,

as Collateral Agent under the Securities Exchange Agreement.	

 
	

By:	

/s/  JOHN BRENNAN      
 Name:  John Brennan

Title:    Trust Officer	

 

 
 

Annex A    
    

	Name of Acceding Holder
 
	 	Principal Amount of exchanged Convertible Notes
	 	Principal Amount of new Notes
	 	Number of Shares into which Warrants are exercisable

	Ferguson, William & Janiece B.	 	 	70,000	 	 	35000	 	6407
	Anepohl, Clarilynn D.	 	 	45,000	 	 	22000	 	4119
	Breaux, Frank W.	 	 	100,000	 	 	50000	 	9153
	Anepohl, Jr., Fred G.	 	 	35,000	 	 	18000	 	3203
	Solar, Curtis J & Kay M	 	 	20,000	 	 	10000	 	1831
	Attrep, John	 	 	90,000	 	 	45000	 	8237
	Balcom, Grace, Randy & Carolyn	 	 	75,000	 	 	37000	 	6864
	Ballard, E. Dwight	 	 	70,000	 	 	35000	 	6407
	Ballard, Dwight & Sandra Jean	 	 	20,000	 	 	10000	 	1831
	Balle, David S	 	 	35,000	 	 	18000	 	3203
	Balliro, Peggy G	 	 	20,000	 	 	10000	 	1831
	Williams, John Kelly	 	 	50,000	 	 	25000	 	4576
	Bayard, William J	 	 	25,000	 	 	13000	 	2288
	Anjier, Joseph L	 	 	90,000	 	 	45000	 	8237
	Bombet MD, Leon H	 	 	100,000	 	 	50000	 	9153
	Borak, Rachel	 	 	35,000	 	 	18000	 	3203
	Brewer, Ralph	 	 	65,000	 	 	32000	 	5949
	Bowman, Edwin A	 	 	35,000	 	 	18000	 	3203
	Burroughs MD, Richard	 	 	175,000	 	 	87000	 	16017
	Hirsch, Gary S. & Karen E	 	 	75,000	 	 	37000	 	6864
	Hirsch, Gary S	 	 	130,000	 	 	65000	 	11898
	Weldon, William E	 	 	170,000	 	 	85000	 	15559
	Weldon, William & Cornelia	 	 	115,000	 	 	57000	 	10525
	Newcomer, JR, George C	 	 	90,000	 	 	45000	 	8237
	Cassidy, Laura	 	 	40,000	 	 	20000	 	3661
	Pace, William Robert	 	 	70,000	 	 	35000	 	6407
	CJS Investments	 	 	25,000	 	 	13000	 	2288
	Claiborne, Earl B.	 	 	110,000	 	 	55000	 	10068
	Claiborne, Earl B. & Ethel L.	 	 	25,000	 	 	13000	 	2288
	Head & Neck P/S Plan, Clinic of	 	 	30,000	 	 	15000	 	2746
	Head & Neck Pension Pln, Clinic	 	 	65,000	 	 	32000	 	5949
	Collins, Steven & Eileen	 	 	30,000	 	 	15000	 	2746
	De Fraites, Rebecca Kay	 	 	20,000	 	 	10000	 	1831
	de Jongh, Maria P	 	 	20,000	 	 	10000	 	1831
	De Fraites JR, Emanuel G	 	 	50,000	 	 	25000	 	4576
	de Jongh, Alberto & Maria	 	 	160,000	 	 	80000	 	14644
	Delhaye Children's Tr II	 	 	65,000	 	 	33000	 	5949
	Mayfield, Mary Jo	 	 	115,000	 	 	57000	 	10525
	Dement, Leon D. & Sylvia L.	 	 	75,000	 	 	37000	 	6864
	Delhaye, Mary Field	 	 	25,000	 	 	13000	 	2288
	Dupont, J. Benton	 	 	115,000	 	 	57000	 	10525
	Dupont MD, J. Benton	 	 	30,000	 	 	15000	 	2746
	Dyer, Herbert R.	 	 	180,000	 	 	90000	 	16475
	Phillips, Gary N	 	 	210,000	 	 	105000	 	19220
	Silverberg, Joel D	 	 	25,000	 	 	13000	 	2288
	Trahan III, Victor "Trey"	 	 	130,000	 	 	65000	 	11898
	Barry, Mary Kathleen V	 	 	200,000	 	 	100000	 	18305
	Cloud, Louise C	 	 	60,000	 	 	30000	 	5492

	Fazio, Frank L	 	 	45,000	 	 	23000	 	4119
	Ferguson, William F	 	 	50,000	 	 	25000	 	4576
	Mayfield FP, Field	 	 	65,000	 	 	32000	 	5949
	Sanders, Donald Leroy	 	 	75,000	 	 	37000	 	6864
	Fleury, JR, Linton Albert	 	 	55,000	 	 	27000	 	5034
	Gasparrini, Sue D	 	 	25,000	 	 	13000	 	2288
	Gasparrini, William G	 	 	65,000	 	 	32000	 	5949
	Mayfield, Drew Generation Skippi	 	 	10,000	 	 	5000	 	915
	Greco, Leu Anne	 	 	50,000	 	 	25000	 	4576
	Greco TTEE, Cyrus John	 	 	100,000	 	 	50000	 	9153
	Grissom MD, Robert T	 	 	25,000	 	 	13000	 	2288
	Grissom MD, Robert T	 	 	15,000	 	 	8000	 	1373
	Greco, Cyrus John	 	 	120,000	 	 	60000	 	10983
	Haga, D Bruce	 	 	25,000	 	 	13000	 	2288
	Hall MD, Donald Leroy	 	 	110,000	 	 	55000	 	10068
	Kennon JR, Robert F	 	 	70,000	 	 	35000	 	6407
	Harner, James Oliver	 	 	70,000	 	 	35000	 	6407
	Hirsch, Karen Elkind	 	 	30,000	 	 	15000	 	2746
	Haydel, Froisin J.	 	 	220,000	 	 	110000	 	20127
	Haydel, F. Joseph & Frances L.	 	 	50,000	 	 	25000	 	4576
	Mayfield Trust, John D.	 	 	25,000	 	 	13000	 	2288
	Bayard, William J & Peggy G	 	 	30,000	 	 	15000	 	2746
	Bayard, William J & Peggy G	 	 	15,000	 	 	8000	 	1373
	Norman, Joseph R.	 	 	95,000	 	 	47000	 	8695
	Norman, Joseph R. & Susan	 	 	15,000	 	 	8000	 	1373
	BCL Investment Partnership	 	 	90,000	 	 	45000	 	8237
	Kirsch JR, William G	 	 	40,000	 	 	20000	 	3661
	Herad, Khosrow	 	 	55,000	 	 	27000	 	5034
	Trahan III "Trey", Victor F	 	 	10,000	 	 	5000	 	915
	Laville, Anne	 	 	50,000	 	 	25000	 	4576
	Laville, Anne M.	 	 	40,000	 	 	20000	 	3661
	Lee, David M	 	 	40,000	 	 	20000	 	3661
	Lee, J. David	 	 	100,000	 	 	50000	 	9153
	Lockwood, Thomas M.	 	 	25,000	 	 	13000	 	2288
	La. Realtors Assoc LDF	 	 	50,000	 	 	25000	 	4576
	Delhaye Trust, Mary Jo	 	 	10,000	 	 	5000	 	915
	Maestri Jr., Natale A	 	 	25,000	 	 	13000	 	2288
	Mayfield, Lucy R	 	 	40,000	 	 	20000	 	3661
	Mayfield, Mary Jane	 	 	95,000	 	 	47000	 	8695
	Cloyd, William P.	 	 	110,000	 	 	55000	 	10068
	McMillin, Bill	 	 	70,000	 	 	35000	 	6407
	McNeil, Edwin B	 	 	50,000	 	 	25000	 	4576
	Mosley, Guy J & Wanda M	 	 	60,000	 	 	30000	 	5492
	Mosley, Guy J	 	 	30,000	 	 	15000	 	2746
	Mosley, Wanda M	 	 	40,000	 	 	20000	 	3661
	Myres, Betty G	 	 	50,000	 	 	25000	 	4576
	Myres, Yancey C	 	 	45,000	 	 	22000	 	4119
	Shannon, Keith D	 	 	40,000	 	 	20000	 	3661
	Noland, Ameila M	 	 	50,000	 	 	25000	 	4576
	Ordeneaux, Jerry C.	 	 	140,000	 	 	70000	 	12814

	Poche, Francis Jay	 	 	15,000	 	 	8000	 	1373
	Pollard, Glenda S	 	 	65,000	 	 	32000	 	5949
	Reine MD, Georgia A	 	 	20,000	 	 	10000	 	1831
	Reine, Georgia A	 	 	175,000	 	 	87000	 	16017
	Richey, Anne Q	 	 	70,000	 	 	35000	 	6407
	Richey, Charles A	 	 	70,000	 	 	35000	 	6407
	Richey, Charles A & Anne Q	 	 	60,000	 	 	30000	 	5492
	Coleman & Partners, Robert	 	 	100,000	 	 	50000	 	9153
	Russo III DDS, Camille Joseph	 	 	60,000	 	 	30000	 	5492
	Russo, Camille J & Patricia	 	 	50,000	 	 	25000	 	4576
	Russo III DDS MPP, Camille J	 	 	90,000	 	 	45000	 	8237
	Rucci, Peter J	 	 	40,000	 	 	20000	 	3661
	Schexnayder, Michael C. & Charl	 	 	25,000	 	 	13000	 	2288
	Schexnayder MD, Michael C.	 	 	60,000	 	 	30000	 	5492
	Schucker, Robert Charles	 	 	170,000	 	 	85000	 	15559
	Schwartzberg, Harvey J	 	 	70,000	 	 	35000	 	6407
	Schwartzberg, Harvey J & Betty	 	 	25,000	 	 	13000	 	2288
	Schwartzberg, Ellis J. & Barb	 	 	55,000	 	 	27000	 	5034
	Shannon, Maureen G	 	 	50,000	 	 	25000	 	4576
	Drake, Kathryn M	 	 	15,000	 	 	8000	 	1373
	Cloyd MD, William P.	 	 	210,000	 	 	105000	 	19220
	Solar, Karen Kay	 	 	30,000	 	 	15000	 	2746
	Mayfield Trust, Lucy R.	 	 	25,000	 	 	12000	 	2288
	Steen, Gayle	 	 	175,000	 	 	87000	 	16017
	Collins TTEE, Steven D	 	 	50,000	 	 	25000	 	4576
	Stark, Michael M	 	 	80,000	 	 	40000	 	7322
	Wood, Danny S.	 	 	15,000	 	 	8000	 	1373
	Cavalier, MD, Steven J.	 	 	110,000	 	 	55000	 	10068
	Alvarez, MD, Frank J.	 	 	100,000	 	 	50000	 	9153
	Schwartzberg, MD, Glen	 	 	85,000	 	 	42000	 	7780
	Robin, MD, Richard L.	 	 	140,000	 	 	70000	 	12814
	Roberts, MD, Floyd J.	 	 	165,000	 	 	82000	 	15102
	Melker MD, Merritt "Trey"	 	 	100,000	 	 	50000	 	9153
	Dement, MD, Leon N.	 	 	190,000	 	 	95000	 	17390
	Gladney, MD, William W.	 	 	100,000	 	 	50000	 	9153
	Peairs, MD, Patricia T.	 	 	35,000	 	 	18000	 	3203
	Hargus, MD, Louis Field	 	 	125,000	 	 	62000	 	11441
	Waggenspack, MD, Mark	 	 	70,000	 	 	35000	 	6407
	Silverberg, MD, Joel	 	 	25,000	 	 	13000	 	2288
	Rolfsen, MD, Michael	 	 	80,000	 	 	40000	 	7322
	Seiter, MD, Elizabeth D.	 	 	90,000	 	 	45000	 	8237
	Vicari, MD, Roberta C.	 	 	50,000	 	 	25000	 	4576
	Vath, MD, Richard R.	 	 	105,000	 	 	52000	 	9610
	Silvey, Edgar H.	 	 	80,000	 	 	40000	 	7322
	Hecker MD, Roger	 	 	35,000	 	 	17000	 	3203
	Earhart MD, Robert N	 	 	115,000	 	 	57000	 	10525
	Vinci, MD, Edmund	 	 	60,000	 	 	30000	 	5492
	Fraser, MD, Warren M.	 	 	125,000	 	 	62000	 	11441
	Thudium, Jr., John F.	 	 	165,000	 	 	82000	 	15102
	Barry, Mary Kathleen	 	 	35,000	 	 	18000	 	3203

	Garcia, O J	 	 	65,000	 	 	32000	 	5949
	Waguespack, Hubert J.	 	 	140,000	 	 	70000	 	12814
	Waguespack, Phillip J.	 	 	100,000	 	 	50000	 	9153
	Wall IV, Williams D	 	 	45,000	 	 	23000	 	4119
	Wall IV, Williams D	 	 	30,000	 	 	15000	 	2746
	Walsh, Robert Eugene	 	 	20,000	 	 	10000	 	1831
	Walsh, Robert & Linda	 	 	50,000	 	 	25000	 	4576
	Williams, John Kelly	 	 	80,000	 	 	40000	 	7322
	Wood, Danny S. & Leah S.	 	 	25,000	 	 	13000	 	2288
	Wood, MD, Danny S.	 	 	110,000	 	 	55000	 	10068
	Bernhard, Jo'An O	 	 	40,000	 	 	20000	 	3661
	Zuckerman, Steven J.	 	 	50,000	 	 	25000	 	4576
	Zuckerman, Steven & Marialden	 	 	45,000	 	 	23000	 	4119
	Allen, Lane	 	 	65,000	 	 	33000	 	5949
	Ashford, Jules	 	 	110,000	 	 	55000	 	10068
	Bradford, Juanita	 	 	75,000	 	 	37000	 	6864
	Ellison, Linda	 	 	50,000	 	 	25000	 	4576
	Gust, Dorothy	 	 	10,000	 	 	5000	 	915
	Gust, Richard	 	 	65,000	 	 	32000	 	5949
	Salter, Barbara	 	 	45,000	 	 	23000	 	4119
	Summers, Steven	 	 	30,000	 	 	15000	 	2746
	Summers, Jane	 	 	10,000	 	 	5000	 	915
	Summers, S & J	 	 	35,000	 	 	17000	 	3203
	

TOTAL:	
 	
$	

11,770,000	
 	
$	

5,884,000	
 	

1,077,248
	

Additional New Notes and Warrants to be held by iBasis until such time as additional Acceding Holders become party to this Joinder Agreement pursuant to Section 9 hereof.	
 	
$
	

430,000

—To be exchanged.	
 	
$	

216,000	
 	

39,357
	
TOTAL:	
 	
 	
12,200,000	
 	
$	

6,100,000	
 	

1,116,605

 
 

Schedule 2    
    

 
 

Schedule of Exceptions    
    

	Name of

Acceding Holder
	 	Principal Amount

of exchanged

Convertible Notes
	 	Principal Amount

of new Notes
	 	Number of Shares

into which Warrants

are exercisable

	Allen, Lane	 	65,000	 	33,000	 	5,949
	Ashford, Jules	 	110,000	 	55,000	 	10,068
	Bradford, Juanita	 	75,000	 	37,000	 	6,864
	Ellison, Linda S	 	50,000	 	25,000	 	4,576
	Gust, Dorothy B	 	10,000	 	5,000	 	915
	Gust, Richard	 	65,000	 	32,000	 	5,949
	Salter, Barbara G	 	45,000	 	23,000	 	4,119
	Summers, Steven Hall	 	30,000	 	15,000	 	2,746
	Summers, Jane Kay	 	10,000	 	5,000	 	915
	Summers, Steven & Jane K	 	35,000	 	17,000	 	3,203

 
 

Annex B    
    

 
 

Instrument of Accession    
    

 
 

[June    , 2003]    
    

        Reference is made to that certain Joinder Agreement dated as of May 29, 2003, a copy of which is attached hereto (as amended and in effect from time to
time, the "Joinder Agreement"), among iBasis, Inc. (the "Company"), iBasis Global, Inc.
("Global" and together with the Company, the "Borrower"), the Acceding Holders as named therein, and U.S. Bank National Association, as Collateral
Agent, Fiscal Agent and Warrant Agent (the "Agent"). 

        The
persons listed on Schedule 1 attached hereto are the owners or holders of the Company's 53/4% Convertible
Subordinated Notes due 2005 and each person hereby agrees that, by his or her execution hereof, that it is an Acceding Holder party to the Joinder Agreement and that he or she is subject to all of the
restrictions and conditions applicable to the Acceding Holders set forth in such Joinder Agreement. This Instrument of Accession shall take effect and shall become a part of said Joinder Agreement
immediately upon acceptance thereof by the Borrower and the Agent. Attached hereto are revised Annex A and  Schedule 2 to the Joinder Agreement.

        Executed
as of the date set forth below under the laws of the Commonwealth of Massachusetts. 

	

 	
 	
ACCEDING HOLDERS

listed on Schedule 1 hereto
	

 	
 	

By:	

COMMONWEALTH ADVISORS, INC.

their attorney in fact
	

 	
 	

By:	

 Name:

Title:

Address;    P.O. Box 3395

                   Baton Rouge, LA 70821

	

Accepted:
 iBASIS, INC.	

 
	
By:	

 Name:

Title:	

 

	iBASIS GLOBAL, INC.	 
	
By:	

 Name:

Title:	

 
	
U.S. BANK NATIONAL ASSOCIATION,

as Collateral Agent under the Securities Exchange Agreement.	

 
	

By:	

 Name:

Title:	

 

 
 

Schedule 1    
    

	Name of

Acceding Holder
	 	Principal Amount

of exchanged

Convertible Notes
	 	Principal Amount

of new Notes
	 	Number of Shares

into which Warrants

are exercisable

[List
the Acceding Holders that are additional parties to the Joinder Agreement pursuant to Section 9 thereof.] 

QuickLinks

Exhibit 10.57

JOINDER AGREEMENT

Annex A

Schedule 2

Schedule of Exceptions

Annex B

Instrument of Accession

[June , 2003]

Schedule 1QuickLinks
 -- Click here to rapidly navigate through this document

 
 

Exhibit 10.58    
    

 
 

iBASIS, INC.
  
    and
  
    the HOLDERS
    
    
    listed on Annex A hereto    
    

 
 

REGISTRATION RIGHTS AGREEMENT
  
    Dated as of May 29, 2003    
    

 
 

TABLE OF CONTENTS    
    

	 
	 	 
	 	Page

	Section 1.	 	Registration Rights	 	1
	

Section 2.	
 	

Definitions	
 	

9
	

Section 3.	
 	

Notices	
 	

10
	

Section 4.	
 	

Successors	
 	

11
	

Section 5.	
 	

Governing Law; Submission to Jurisdiction: Waiver of Jury Trial	
 	

11
	

Section 6.	
 	

Exercise of Rights and Remedies	
 	

11
	

Section 7.	
 	

Benefits of This Agreement	
 	

11
	

Section 8.	
 	

Counterparts	
 	

12
	

Section 9.	
 	

Additional Parties	
 	

12

        REGISTRATION RIGHTS AGREEMENT (this "Agreement"), dated as of May 29, 2003, between (i) iBasis, Inc., a Delaware
corporation (the "Company"), (ii) the persons listed on Annex A hereto (the
"Initial Holders"), and (iii) each other Person who becomes a party to this Agreement pursuant to Section 9 hereof (such other Persons
together with the Initial Holders, the "Holders"). Capitalized terms used herein and not otherwise defined shall have the meaning ascribed to such terms
in Section 2 hereof. 

        WHEREAS,
the Company proposes to issue to the Holders (i) the Commonwealth Warrants, which in the aggregate initially entitle the Holders to purchase, 1,116,605 shares of Common
Stock of the Company on May 29, 2003, and (ii) the Commonwealth Notes, in the aggregate principal amount of $6,100,000, in each case pursuant to a Joinder Agreement (dated as of
May 29, 2003, by and among the Company, iBasis Global, Inc., the Holders and U.S. Bank National Association, as Collateral Agent (the "Joinder
Agreement")) to that certain Securities Exchange Agreement, dated as of February 21, 2003, among the Company, iBasis Global, Inc., the guarantors named therein,
JMG Triton Offshore Limited Fund CITCO and U.S. Bank National Association, as Collateral Agent (as amended, supplemented and otherwise modified from time to time, the
"Securities Exchange Agreement"). 

        WHEREAS,
the Company and the Holders desire to enter into this Agreement to provide the Holders registration rights with respect to the Commonwealth Warrants and the Commonwealth Notes. 

        WHEREAS,
the Commonwealth Warrants and the Commonwealth Notes shall have registration rights as provided herein. 

        NOW,
THEREFORE, in consideration of the premises and the mutual agreements herein set forth, the parties hereto agree as follows: 

        Section
1.    Registration Rights.    The Company will perform and comply, and cause each of its Subsidiaries to
perform and comply, with each of the following provisions as are applicable to it. Each Holder will perform and comply with each of the following provisions as are applicable to such holder. 

        1.1    Demand Registration Rights.    

        1.1.1.    General.    At any time after July 30, 2003, one or more holders of (i) the Commonwealth
Warrants who at such time hold greater than 20% of the Commonwealth Warrants (determined based on an as-exercised basis), or (ii) the Commonwealth Notes who at such time hold
greater than 20% of the aggregate principal amount of the Commonwealth Notes (in either case, the "Initiating Holders"), may request, by written notice
to the Company, that the Company effect the registration under the Securities Act for a Public Offering of all or a specified part of the Registrable Securities held by such Initiating Holders. Such
notice shall specify the intended method or methods of distribution and the type of Registrable Securities intended to be so registered. Promptly after receipt of such notice from the Initiating
Holders, the Company shall give notice of such requested registration to all other holders of Registrable Securities in accordance with Section 1.2. The Company will then use its reasonable
best efforts to effect the registration under the Securities Act of the Registrable Securities which the Company has been requested to register by such Initiating Holders, together with all other
Registrable Securities which the Company has been requested to register pursuant to Section 1.2 or otherwise by notice delivered to the Company within 20 days after the Company has given
the required notice of such requested registration (which request shall specify the intended method of disposition of such Registrable Securities), all to the extent requisite to permit the
disposition (in accordance with the intended methods thereof as aforesaid) of the Registrable Securities which the Company has been so requested to register; provided,
however, that the Company shall not be obligated to take any action to effect any such registration pursuant to this Section 1.1.1 within 180 days immediately
following the effective date of any registration statement pertaining to an underwritten public offering of securities of the Company for its own account (other than a Rule 145 Transaction, or
a registration relating solely to employee benefit plans). 

 

        1.1.2.    Form; Limitations.    Except as otherwise provided above, each registration requested pursuant to
Section 1.1.1 shall be effected by the filing of a registration statement on Form S-1 (or any other form which includes substantially the same information as would be
required to be included in a registration statement on such form as currently constituted), unless the use of a different form has been agreed to in writing by holders of at least a majority of the
Registrable Securities to be included in the proposed registration statement in question (the "Majority Participating Holders") or the Company is then
eligible to use Form S-3 for a Public Offering by the Majority Participating Holders of their Registrable Securities; provided,
however, that the Company shall not be required to effect any registration requested pursuant to Section 1.1.1 on any form other than Form S-3 (or any
successor form) if the Company has previously effected three or more registrations of Registrable Securities under Section 1.1.1 on any form other than Form S-3 (or any
successor form). No registration of Registrable Securities which shall not have become and remained effective in accordance with this Section 1.1 shall be included in the calculation of the
number of registrations contemplated by this Section 1.1.2 (unless the Initiating Holders withdraw their request for such registration, other than (i) if such withdrawal is a result of
information concerning the business or financial condition of the Company which is made known after the date on which such registration was requested or (ii) if the Initiating Holders pay all
the expenses of such registration otherwise payable by the Company pursuant to Section 1.1.3). If at the time of any request to register Registrable Securities pursuant to this
Section 1.1.1, the Company is engaged or has plans to engage in a registered public offering or is engaged in any other activity which, in the good
faith determination of the Board, would be adversely affected by the requested registration, then the Company may at its option direct that such request be delayed for a period not in excess of
30 days from the date of such request, such right to delay a request to be exercised by the Company not more than once in any 12-month period. In the event that, in the judgment of
the Company, it is advisable to suspend use of a prospectus included in a registration statement due to pending material developments or other events that have not yet been publicly disclosed and as
to which the Company believes public disclosure would be detrimental to the Company, the Company shall notify all selling stockholders to such effect, and, upon receipt of such notice, each such
selling stockholder shall immediately discontinue any sales of Registrable Securities pursuant to such registration statement until such selling stockholder has received copies of a supplemented or
amended prospectus or until such selling stockholder is advised in writing by the Company that the then current prospectus may be used and has received copies of any additional or supplemental filings
that are incorporated or deemed incorporated by reference in such prospectus. Notwithstanding anything to the contrary herein, the Company shall not exercise its rights under the foregoing sentence to
suspend sales of Registrable Securities for a period in excess of 30 days consecutively or 60 days in any 365-day period. 

        1.1.3.    Payment of Expenses.    The Company shall pay all reasonable expenses of holders of Registrable Securities
incurred in connection with the first three registrations of Registrable Securities requested pursuant to this Section 1.1 (including the reasonable fees and expenses of a single legal counsel
representing all selling stockholders), other than underwriting discounts and commissions, if any, and applicable transfer taxes, if any. 

        1.1.4.    Additional Procedures.    In the case of a registration pursuant to Section 1.1.2, whenever the
Initiating Holders shall request that such registration shall be effected pursuant to an underwritten offering, the Company shall include such information in the written notices to holders of
Registrable Securities referred to in Section 1.1.2. In such event, the right of any holder of Registrable Securities to have securities owned by such holder included in such registration
pursuant to this Section 1.1.1 shall be conditioned upon such holder's participation in such underwriting and the inclusion of such holder's Registrable Securities in the 

2

 

underwriting
(unless otherwise mutually agreed upon by the Majority Participating Holders and such holder). If requested by the underwriters of such registration, the Company, together with the
holders of Registrable Securities proposing to distribute their securities through such underwriting, will enter into an underwriting agreement with such underwriters for such offering containing such
representations and warranties by the Company and such holders and such other terms and provisions as are customarily contained in underwriting agreements with respect to secondary distributions,
including, without limitation, customary indemnity and contribution provisions (subject, in each case, to the limitations on such liabilities set forth in this Agreement). 

        1.2    Piggyback Registration Rights.    

        1.2.1    General.    Each time the Company proposes to register any of its securities under the Securities Act on a
form which would permit registration of Registrable Securities for sale to the public, for its own
account and/or for the account of any holders of Registrable Securities or Affiliate of a holder of Registrable Securities (pursuant to Section 1.1 or otherwise), for sale in a Public Offering,
the Company will give notice to all holders of Registrable Securities of its intention to do so. Any such holder may, by written response delivered to the Company within 20 days after the
effectiveness of such notice, request that all or a specified part of the Registrable Securities held by such holder of the same type of Registrable Securities to be so registered by the Company be
included in such registration. The Company thereupon will use its reasonable efforts to cause to be included in such registration under the Securities Act all such Registrable Securities which the
Company has been so requested to register by such holders, to the extent required to permit the disposition (in accordance with the methods to be used by the Company or other holders of its securities
in such Public Offering) of the Registrable Securities to be so registered. No registration of Registrable Securities effected under this Section 1.2 shall relieve the Company of any of its
obligations to effect registrations of Registrable Securities pursuant to Section 1.1. The Company may withdraw or suspend any registration covered by this Section 1.2 at any time
(subject, in the case of any registration also covered by Section 1.1, to any limitations set forth therein). 

        1.2.2.    Excluded Transactions.    The Company shall not be obligated to effect any registration of Registrable
Securities under this Section 1.2 incidental to the registration of any of its securities in connection with: 

        (a)   Any
Public Offering relating to employee benefit plans or dividend reinvestment plans; or 

        (b)   Any
Public Offering relating to the acquisition or merger after the date hereof by the Company or any of its Subsidiaries of or with any other businesses. 

        1.2.3.    Payment of Expenses.    The Company shall pay all reasonable fees and expenses of a single legal counsel
representing any and all holders of Registrable Securities incurred in connection with the first three registrations of Registrable Securities requested pursuant to this Section 1.2. 

        1.2.4.    Additional Procedures.    Holders of Registrable Securities participating in any Public Offering pursuant to
this Section 1.2 shall take all such actions and execute all such documents and instruments that are reasonably requested by the Company to effect the sale of their Registrable Securities in
such Public Offering, including, without limitation, being parties to the underwriting agreement entered into by the Company and any other selling securityholders in connection therewith and being
liable in respect of the representations and warranties by, and the other agreements (including without limitation customary selling 

3

 

securityholder
representations, warranties, indemnifications and "lock-up" agreements) for the benefit of the underwriters; provided,
however, that (a) with respect to individual representations, warranties, indemnities and agreements of selling holders of Registrable Securities in such Public
Offering, the aggregate amount of such liability shall not exceed such holder's net proceeds from such offering and (b) to the extent selling holders of Registrable Securities give further
representations, warranties and indemnities, then with respect to all other representations, warranties and indemnities of sellers of securities in such Public Offering, the aggregate amount of such
liability shall not exceed the lesser of (i) such holder's pro rata portion of any such liability, in accordance with such holder's portion of the total number of Registrable Securities
included in the offering or (ii) such holder's net proceeds from such offering. 

        1.3.    Certain Other Provisions.    

        1.3.1.    Underwriter's Cutback.    In connection with any registration of Registrable Securities, the underwriter may
determine that marketing factors (including, without limitation, an adverse effect on the per share offering price) require a limitation of the number of Registrable Securities to be underwritten.
Notwithstanding any contrary provision of Section 1.1 or Section 1.2, and subject to the terms of this Section 1.3.1, the underwriter may limit the number of securities which
would otherwise be included in such registration by excluding any or all Registrable Securities from such registration (it being understood that the number of securities which the Company seeks to
have registered in such registration shall not be subject to exclusion, in whole or in part, under this Section 1.3.1). Upon receipt of notice from the underwriter of the need to reduce the
number of securities to be included in the registration, the Company shall advise all holders of the Company's securities that would otherwise be registered and underwritten pursuant hereto, and the
number of such securities, including Registrable Securities, that may be included in the registration shall be allocated in the following manner, unless the underwriter shall determine that marketing
factors require a different allocation: (i) securities, other than Registrable Securities, requested to be included in such registration by securityholders shall be excluded unless
(x) the Company has, prior to the date hereof, or after the date hereof with the consent of the Majority Holders, granted registration rights which are to be treated on an equal basis with
Registrable Securities for the purpose of the exercise of the underwriter cutback (with it being specifically agreed and acknowledged that the registration rights granted to Silicon Valley Bank
pursuant to the Registration Rights Agreement, dated on or around December 30, 2002, between the Company and Silicon Valley Bank are to be treated on an equal basis with Registrable Securities
for the purposes of this underwriting cutback), or (y) such securities are issued in connection with a Permitted Exchange (as defined in the Securities Exchange Agreement), with it being
specifically acknowledged that the registration rights granted to the holders of any such securities are to be treated on an equal basis with Registrable Securities for purposes of this underwriting
cutback; and (ii) if further limitation on the number of securities to be included in the offering is required, the number of Registrable Securities and other securities that may be included in
such registration shall be allocated among holders thereof in proportion, as nearly as practicable, to the respective amounts of securities which each securityholder requested be registered in such
registration. No securities excluded from the underwriting by reason of the underwriter's marketing limitation shall be included in such registration. Upon delivery of a written request that
Registrable Securities be included in an underwritten offering pursuant to Section 1.1.1 or Section 1.2.1, the holder thereof may not thereafter (i) elect to withdraw therefrom
without the written consent the Company and the Majority Participating Holders, or (ii) exchange, convert or exercise, as the case may be, such Registrable Securities. 

4

 

        1.3.2.    Registration Procedures.    If and in each case when the Company is required to use its reasonable best
efforts to effect a registration of any Registrable Securities as provided in Section 1.1 or Section 1.2, the Company shall take appropriate and customary actions in furtherance thereof,
including, without limitation: 

        (a)   promptly
filing with the Commission a registration statement and using best efforts to cause such registration statement to become effective; 

        (b)   preparing
and filing with the Commission such amendments and supplements to such registration statements as may be required to comply with the Securities Act and to keep
such registration
statement effective for a period not to exceed 270 days from the date of effectiveness or such earlier time as the Registrable Securities covered by such registration statement shall have been
disposed of in accordance with the intended method of distribution therefor or the expiration of the time when a prospectus relating to such registration is required to be delivered under the
Securities Act; provided, however, that if the registration is effected by the filing of a registration statement on Form S-3, then
the Company shall keep such registration statement effective for a period not to exceed 3 years from the date of effectiveness or such earlier time as the Registrable Securities covered by such
registration statement have been disposed of in accordance with the intended method of distribution therefore, the expiration of the time when a prospectus relating to such registration is required to
be delivered under the Securities Act, or such registration statement no longer covers Registrable Securities; 

        (c)   using
its best efforts to register or qualify such Registrable Securities under the state securities or "blue sky" laws of such jurisdictions as the sellers shall
reasonably request; provided, however, that the Company shall not be obligated to file any general consent to service of process or to qualify as a
foreign corporation in any jurisdiction in which it is not so qualified or to subject itself to taxation in respect of doing business in any jurisdiction in which it would not otherwise be so subject;
and 

        (d)   otherwise
cooperating reasonably with, and taking such customary actions as may reasonably be requested by the holders of Registrable Securities in connection with, such
registration. 

        1.3.3.    Selection of Underwriters and Counsel.    The underwriters and legal counsel to be retained in connection
with any Public Offering shall be selected by the Board or, in the case of an offering following a request therefor under Section 1.1.1, the Initiating Holders with the consent of the Company
(which consent shall not be unreasonably withheld). 

        1.3.4.    Lock-Up.    Without the prior written consent of the underwriters managing any Public Offering,
for a period beginning seven days immediately preceding and ending on the 90th day following the effective date of the registration statement used in connection with such offering, no holder of
Commonwealth Warrants (whether or not a selling securityholder pursuant to such registration statement) representing (on an as-exercised basis) at least 1% of the outstanding Common Stock
shall (a) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or
otherwise transfer, directly or indirectly, any shares of Common Stock or any securities convertible into or exercisable or exchangeable for such Common Stock or (b) enter into any swap or
other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of Common Stock, whether any such transaction described in clause (a) or
(b) above is to be settled by delivery of such Common Stock or such other securities, in cash or otherwise; provided, however, that the foregoing
restrictions shall not apply to (i) the sale of Commonwealth Warrants pursuant to any such registration statement filed in accordance with Section 1.1 or Section 1.2;
(ii) transactions 

5

 

relating
to shares of Common Stock or other securities acquired in open market transactions; or (iii) the exercise, conversion or exchange of Commonwealth Warrants or conversions of shares of
Common Stock into other classes of Common Stock without change of holder. 

        1.3.5.    Future Registration Rights.    If, after the date hereof, the Company enters into an agreement or other
commitment with any other Person that has the effect of establishing registration rights with respect to the Company's securities the terms of which are more favorable, taken as a whole, to such
Person than the registration rights established in favor of the holders of Registrable Securities pursuant to Section 1.1 or Section 1.2, then the Company will promptly so notify such
holders in writing, and the Company shall, without the necessity of any action on the part of such holders, extend the benefits of such more favorable terms to such holders as if such terms were
contained in this Agreement, or permit such holders to enter into such other agreement establishing such rights in lieu of this agreement. 

        1.4.    Indemnification and Contribution.    

        1.4.1.    Indemnities of the Company.    In the event of any registration of any Registrable Securities or other debt
or equity securities of the Company or any of its Subsidiaries under the Securities Act pursuant to Section 1.1, Section 1.2 or otherwise, and in connection with any registration
statement or any other disclosure document produced by or on behalf of the Company or any of its Subsidiaries including, without limitation, reports required and other documents filed under the
Exchange Act, and other documents pursuant to which any debt or equity securities of the Company or any of its Subsidiaries are sold (whether or not for the account of the Company or its
Subsidiaries), the Company will, and hereby does, and will cause each of its Subsidiaries, jointly and severally, to indemnify and hold harmless each seller of Registrable Securities, any Person who
is or might be deemed to be a controlling Person of the Company or any of its Subsidiaries within the meaning of section 15 of the Securities Act or section 20 of the Exchange Act, their
respective direct and indirect partners, advisory board members, directors, officers, trustees, members and stockholders, and each other Person, if any, who controls any such seller or any such
controlling Person within the meaning of section 15 of the Securities Act or section 20 of the Exchange Act (each such person being referred to herein as a
"Covered Person"), against any losses, claims, damages or liabilities (or actions or proceedings in respect thereof), joint or several, to which such
Covered Person may be or become subject under the Securities Act, the Exchange Act, any other securities or other law of any jurisdiction, the common law or otherwise, insofar as such losses, claims,
damages or liabilities (or actions or proceedings in respect thereof) arise out of or are based upon (i) any untrue statement or alleged untrue statement of any material fact contained or
incorporated by reference in any registration statement under the Securities Act, any preliminary prospectus or final prospectus included therein, or any related summary prospectus, or any amendment
or supplement thereto, or any document incorporated by reference therein, or any other such disclosure document (including without limitation reports and other documents filed under the Exchange Act
and any document incorporated by reference therein) or other document or report, (ii) any omission or alleged omission to state therein a material fact required to be stated therein or
necessary to make the statements therein not misleading or (iii) any violation or alleged violation by the Company or any of its subsidiaries of any federal, state, foreign or common law rule
or regulation applicable to the Company or any of its Subsidiaries and relating to action or inaction in connection with any such registration, disclosure document or other document or report, and
will reimburse such Covered Person for any legal or any other reasonable expenses incurred by it in connection with investigating or defending any such loss, claim, damage, liability, action or
proceeding; provided, however, that neither the Company nor any of its Subsidiaries shall be liable to any Covered Person in any such case to the extent
that any such loss, claim, damage, liability, 

6

 

action
or proceeding arises out of or is based upon an untrue statement or alleged untrue statement or omission or alleged omission made in such registration statement, preliminary prospectus, final
prospectus, summary prospectus, amendment or supplement, incorporated document or other such disclosure document or other document or report, in reliance upon and in conformity with written
information furnished to the Company or to any of its Subsidiaries through an instrument duly executed by such Covered Person specifically stating that it is for use in the preparation thereof. The
indemnities of the Company and of its subsidiaries contained in this Section 1.4.1 shall remain in full force and effect regardless of any investigation made by or on behalf of such Covered
Person and shall survive any transfer of securities. 

        1.4.2.    Indemnities to the Company.    The Company and any of its Subsidiaries may require, as a condition to
including any securities in any registration statement filed pursuant to this Agreement, that the Company and any of its Subsidiaries shall have received an undertaking satisfactory to it from the
prospective seller of such securities, to indemnify and hold harmless the Company and any of its Subsidiaries, each director of the Company or any of its Subsidiaries, each officer of the Company or
any of its Subsidiaries who shall sign such registration statement and each other Person (other than such seller), if any, who controls the Company and any of its Subsidiaries within the meaning of
section 15 of the Securities Act or section 20 of the Exchange Act and each other prospective seller of such securities with respect to any statement in or omission from such
registration statement, any preliminary prospectus, final prospectus or summary prospectus included therein, or any amendment or supplement thereto, or any other disclosure document (including,
without limitation, reports and other documents filed under the Exchange Act or any document incorporated therein) or other document or report, if such statement or omission was made in reliance upon
and in conformity with written information furnished to the Company or any of its Subsidiaries through an instrument executed by such seller specifically stating that it is for use in the preparation
thereof. Such indemnity shall remain in full force and effect regardless of any investigation made by or on behalf of the Company, any of its Subsidiaries or any such director, officer or controlling
Person and shall survive any transfer of securities. 

        1.4.3.    Contribution.    If the indemnification provided for in Section 1.4.1 or Section 1.4.2 hereof
is unavailable to a party that would have been entitled to indemnification pursuant to the foregoing provisions of this Section 1.4 (an
"Indemnitee") in respect of any losses, claims, damages or liabilities (or actions or proceedings in respect thereof) referred to therein, then each
party that would have been an indemnifying party thereunder shall, in lieu of indemnifying such Indemnitee, contribute to the amount paid or payable by such Indemnitee as a result of such losses,
claims, damages or liabilities (or actions or proceedings in respect thereof) in such proportion as is appropriate to reflect the relative fault of such indemnifying party on the one hand and such
Indemnitee on the other in connection with the statements or omissions which resulted in such losses, claims, damages or liabilities (or actions or proceedings in respect thereof). The relative fault
shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to
information supplied by such indemnifying party or such Indemnitee and the parties' relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission.
The parties agree that it would not be just or equitable if contribution pursuant to this Section 1.4.3 were determined by pro rata allocation or by any other method of allocation which does
not take account of the equitable considerations referred to in the preceding sentence. The amount paid or payable by a contributing party as a result of the losses, claims, damages or liabilities (or
actions or proceedings in respect thereof) referred to above in this Section 1.4.3 shall include any legal or other expenses reasonably incurred by such Indemnitee in connection with 

7

 

investigating
or defending any such action or claim. No Person guilty of fraudulent misrepresentation (within the meaning of section 11(f) of the Securities Act) shall be entitled to
contribution from any Person who was not guilty of such fraudulent misrepresentation. 

        1.4.4.    Limitation on Liability of Holders of Registrable Securities.    The liability of each holder of Registrable
Securities in respect of any indemnification or contribution obligation of such holder arising under this Section 1.4 shall not in any event exceed an amount equal to the net proceeds to such
holder (after deduction of all underwriters' discounts and commissions) from the disposition of the Registrable Securities disposed of by such holder pursuant to such registration. 

        1.5    Reports Under Exchange Act.    In order to provide to the holders of Registrable Securities the benefits of
Rule 144 and any other rule or regulation of the Commission that may at any time permit any such holder to sell securities of the Company to the public without registration, and in order to
make it possible for the holders of Registrable Securities to register the sale of the Registrable Securities pursuant to a registration on Form S-3, the Company agrees to: 

        (a)   make
and keep public information available, as those terms are understood and defined in Rule 144; 

        (b)   take
such action, including the registration of its Common Stock under section 12 of the Exchange Act, as is necessary to enable the holders of Registrable
Securities to utilize Form S-3 for the sale of their Registrable Securities (ignoring, for this purpose, the provisions of Items I.A.5 and I.B.3 of the General Instructions
thereto); 

        (c)   file
with the Commission in a timely manner all reports and other documents required of the Company under the Securities Act and the Exchange Act; and 

        (d)   furnish
to any holder of Registrable Securities, so long as the holder owns any Registrable Securities, forthwith upon request (i) a written statement by the
Company that it has complied with the reporting requirements of Rule 144, the Securities Act and the Exchange Act, or that it qualifies as a registrant whose securities may be resold in a
secondary offering pursuant to Form S-3; (ii) a copy of the most recent annual or quarterly report of the Company filed with the Commission and such other reports and
documents so filed by the Company; and (iii) such other information as may be reasonably requested in availing any holder of Shares any rule or regulation of the Commission which permits the
selling of any such securities without registration or pursuant to such form. 

8

   
        Section 2.    Definitions.    For the purposes of this Agreement, the following terms have the meanings below:

        "Affiliate" shall mean, with respect to the Company or any of its Subsidiaries (or any other specified Person), any other Person which,
directly or indirectly controls or is controlled by or is under direct or indirect common control with the Company or such Subsidiary (or such specified Person), and, without limiting the generality
of the foregoing, shall include (a) any other Person which beneficially owns or holds 10% of more of any class of voting securities of such Person or 10% or more of the equity interest in such
Person, (b) any other Person of which such Person beneficially owns or holds 10% or more of any class of voting securities or in which such Person beneficially owns or holds 10% or more of the
equity interest in such Person and (c) any director or executive officer of such Person. For the purposes of this definition, the term "control" (including, with correlative meanings, the terms
"controlled by" and "under common control with"), as used with respect to any Person, means the possession, directly or indirectly, of the power to direct or cause the direction of the management and
policies of such Person, whether through the ownership of voting securities or by contract or otherwise. 

        "Agreement" shall have the meaning set forth in the first paragraph of this Agreement. 

        "Board" shall mean the Board of Directors of the Company. 

        "Commission" shall mean the Securities and Exchange Commission. 

        "Common Stock" shall mean the Company's common stock, par value $0.001 per share. 

        "Commonwealth Notes" shall mean an aggregate principal amount of [$6,100,000] of the Company's 11.5% Senior
Secured Notes due 2005 issued by the Company to the Holders pursuant to the Securities Exchange Agreement (in connection with the execution of the Joinder Agreement). 

        "Commonwealth Warrants" shall mean the warrants to purchase an aggregate of [1,116,605] shares of Common Stock of
the Company issued by the Company to the Holders pursuant to the Securities Exchange Agreement (in connection with the
execution of the Joinder Agreement) (including any Warrant Certificates subsequently issued upon transfer thereof or an exchange therefor from time to time). 

        "Company" has the meaning set forth in the first paragraph of this Agreement. 

        "Covered Person" shall have the meaning set forth in Section 1.4.1. 

        "Exchange Act" shall mean the Securities Exchange Act of 1934, as in effect from time to time. 

        "Holders" has the meaning set forth in the first paragraph of this Agreement and, for purposes of this Agreement, shall include any
permitted transferees of such Holders which subsequently acquire Commonwealth Notes or Commonwealth Warrants. 

        "Indemnitee" shall have the meaning set forth in Section 1.4.3. 

        "Initiating Holder" shall have the meaning set forth in Section 1.1.1. 

        "Joinder Agreement" has the meaning set forth in the second paragraph of this Agreement. 

        "Majority Holders" shall mean, as of any date, collectively, the holders of a majority of (i) the Commonwealth Warrants (determined
on an as-exercised for cash basis), and (ii) the Commonwealth Notes (determined based on the aggregate principal amount), in each
case outstanding on such date. 

        "Majority Participating Holders" shall have the same meaning set forth in Section 1.1.2. 

9

 

        "Person" shall mean an individual, a corporation, a partnership, a limited liability company, a trust, an unincorporated organization or a
government organization or an agency or political subdivision thereof. 

        "Public Offering" shall mean a public offering and sale of securities of the Company for cash pursuant to an effective registration
statement under the Securities Act. 

        "Registrable Securities" shall mean the Commonwealth Warrants and the Commonwealth Notes and all securities directly or indirectly issued
or issuable with respect to the Commonwealth Warrants or the Commonwealth Notes, as the case may be, by way of a recapitalization, merger, consolidation or other reorganization;  provided, however, that
securities which are Registrable Securities shall cease to be Registrable Securities (i) upon any sale pursuant to a
registration statement or Rule 144 under the Securities Act or (ii) at such time as they become eligible for sale pursuant to Rule 144(k) under the Securities Act. Registrable
Securities shall also include the Company's securities of any other Person that joins this Agreement pursuant to Section 9 below. 

        "Rule 144" shall mean Rule 144 under the Securities Act (or any successor Rule). 

        "Rule 145 Transaction" shall mean a registration on Form S-4 pursuant to Rule 145 of the Securities Act (or any
successor Form or provision, as applicable). 

        "Securities Act" shall mean the Securities Act of 1933, as in effect from time to time. 

        "Securities Exchange Agreement" shall have the meaning set forth in the second paragraph of this Agreement. 

        "Subsidiary" shall mean, for any Person, (i) a corporation a majority of whose voting stock is at the time, directly or indirectly,
owned by such Person, by one or more Subsidiaries of such Person or by such Person and one or more Subsidiaries of such Person, (ii) a partnership in which such Person or a Subsidiary of such
Person is, at the date of determination, a general or limited partner of such partnership, but only if such Person or its Subsidiary is entitled to receive more than 50% of the assets of such
partnership upon its dissolution, (iii) a limited liability company, a majority of whose membership interests is, at the time, directly or indirectly owned by such Person or with respect to
which such Person has a right, under any scenario, to receive 50% or more of the distributions of the assets of such limited liability company upon its dissolution, or (iv) any other Person
(other than a corporation or partnership) in which such Person, a Subsidiary of such Person or such Person and one or more Subsidiaries of such Person, directly or indirectly, at the date of
determination thereof, has (a) at least a majority ownership interest or (b) the power to elect or direct the election of a majority of the directors or other governing body of such
Person. 

        "Warrant Certificates" shall mean certificates evidencing the Commonwealth Warrants (or evidencing such new warrants issued upon the
exchange or transfer thereof). 

        Section
3.    Notices.    Any notice or demand authorized by this Agreement to be given or made by any Holder to or on
the Company shall be sufficiently given or made when and if delivered by facsimile transmission (provided confirmation of receipt is received immediately thereafter) or when received, if deposited in
the mail, first class or registered, postage prepaid, addressed (until another address is filed in writing by the Company with the Holders), as follows: 

iBasis,
Inc.

20 Second Avenue

Burlington, MA 01803

Attention: Chief Financial Officer

Facsimile No.: 781-505-7304 

with
a copy to: 

10

 

Bingham
McCutchen LLP

1900 University Avenue

East Palo Alto, CA 94303-2223

Attn: Johan V. Brigham

Facsimile No.: 650-849-4800 

        Any
notice pursuant to this Agreement to be given by the Company to any Holder shall be sufficiently given when and if delivered by facsimile transmission (provided confirmation of
receipt is received immediately thereafter) or deposited in the mail, first-class or registered, postage prepaid, addressed (until another address is filed in writing by such Holder with the Company),
as follows: 

Commonwealth
Advisors, Inc.

P.O. Box 3395

Baton Rouge, LA 70821

Facsimile No.: 225-343-1645 

        Section
4.    Successors.    All the covenants and provisions of this Agreement by or for the benefit of the Company
shall bind and inure to the benefit of its successors and assigns hereunder. 

        Section
5.    Governing Law; Submission to Jurisdiction: Waiver of Jury Trial.    This Agreement shall be deemed to be
a contract made under the laws of The Commonwealth of Massachusetts and for all purposes shall be governed by and construed in accordance with the internal laws of said Commonwealth, without regard to
principles of conflicts of laws. Each party hereto hereby submits to the nonexclusive jurisdiction of the United States District Court for the District of Massachusetts and of any Massachusetts state
court sitting in Boston for purposes of all legal proceedings arising out of or relating to this agreement or the transactions contemplated hereby. Each party hereto irrevocably waives, to the fullest
extent permitted by law, any objection which it may now or hereafter have to the laying of the venue of any such proceeding brought in such a court and any claim that any such proceeding brought in
such a court has been brought in an inconvenient forum. 

        TO
THE EXTENT NOT PROHIBITED BY APPLICABLE LAW WHICH CANNOT BE WAIVED, EACH PARTY HERETO HEREBY WAIVES AND COVENANTS THAT IT WILL NOT ASSERT (WHETHER AS PLAINTIFF, DEFENDANT OR
OTHERWISE) ANY RIGHT TO TRIAL BY JURY IN ANY FORUM IN RESPECT OF ANY ISSUE OR ACTION, CLAIM, CAUSE OF ACTION OR SUIT (IN CONTRACT, TORT OR OTHERWISE), INQUIRY, PROCEEDING OR INVESTIGATION ARISING OUT
OF OR BASED UPON THIS AGREEMENT OR THE SUBJECT MATTER HEREOF OR IN ANY WAY CONNECTED WITH OR RELATED OR INCIDENTAL TO THE TRANSACTIONS CONTEMPLATED HEREBY, IN EACH CASE WHETHER NOW EXISTING OR
HEREAFTER ARISING. EACH PARTY HERETO ACKNOWLEDGES THAT IT HAS BEEN INFORMED BY THE OTHER PARTIES HERETO THAT THIS SECTION 5 CONSTITUTES A MATERIAL INDUCEMENT UPON WHICH THEY ARE RELYING AND WILL RELY
IN ENTERING INTO THIS AGREEMENT. Any party hereto may file an original counterpart or a copy of this Section 5 with any court as written evidence of the consent of each party hereto to the
waiver of its right to trial by jury. 

        Section
6.    Exercise of Rights and Remedies.    No delay of or omission in the exercise of any right, power or
remedy accruing to any party as a result of any breach or default by any other party under this Agreement shall impair any such right, power or remedy, nor shall it be construed as a waiver of or
acquiescence in any such breach or default, or of any similar breach or default occurring later; nor shall any such delay, omission or waiver of any single breach or default be deemed a waiver of any
other breach or default occurring before or after that waiver. 

        Section
7.    Benefits of This Agreement.    Nothing in this Agreement shall be construed to give to any Person or
corporation other than the Company and the Holders (including any holder of a 

11

 

beneficial
interest in any Commonwealth Warrant or Commonwealth Note) any legal or equitable right, remedy or claim under this Agreement, and this Agreement shall be for the sole and exclusive benefit
of the Company and the Holders (including any holder of a beneficial interest in any Commonwealth Warrant or Commonwealth Note). 

        Section
8.    Counterparts.    This Agreement may be executed in any number of counterparts and each of such
counterparts shall for all purposes be deemed to be an original, and all such counterparts shall together constitute but one and the same instrument. 

        Section
9.    Additional Parties.    Any Person that is a holder of the Company's 11.5% Senior Secured Notes due 2005
and/or warrants issued in connection with an exchange of such notes may become a party to this Agreement by executing and delivering to the Company an Instrument of Accession, substantially in the
form of Annex B attached hereto, provided that the Company consents to such Person becoming a party to
this Agreement (which consent shall be conclusively deemed to have been given by the Company if and when the Company countersigns the Instrument of Accession executed by such Person). Any such
Instrument of Accession executed by any such Person and countersigned by the Company shall become a part of this Agreement. It is hereby understood and agreed that such Person may become a party to
this Agreement without having to obtain the signature, consent, approval or permission of any of the parties hereto other than the Company and that, immediately upon such Person becoming a party to
this Agreement, such Person shall be deemed to be a Holder, and Annex A shall be updated automatically without any action required by the parties
hereto. 

[Signature Page Follows]

12

        IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be duly executed, as of the day and year first above written. 

	 	 	iBASIS, INC.
	

 	
 	

By:	

/s/  OFER GNEEZY      
 Ofer Gneezy
 President & CEO
	

 	
 	

HOLDERS listed on Annex A hereto
	

 	
 	

By:	
COMMONWEALTH ADVISORS, INC.

THEIR ATTORNEY IN FACT
	

 	
 	
By:	

/s/  WALTER MORALES      
 Walter Morales
 President

 
 

Annex A    
    

 
 

Holders    
    

	Name of Acceding Holder
 
	 	Number of Shares

into which Warrants

are exercisable

	Ferguson, William & Janiece B.	 	6407
	Anepohl, Clarilynn D.	 	4119
	Breaux, Frank W.	 	9153
	Anepohl, Jr., Fred G.	 	3203
	Solar, Curtis J & Kay M	 	1831
	Attrep, John	 	8237
	Balcom, Grace, Randy & Carolyn	 	6864
	Ballard, E. Dwight	 	6407
	Ballard, Dwight & Sandra Jean	 	1831
	Balle, David S	 	3203
	Balliro, Peggy G	 	1831
	Williams, John Kelly	 	4576
	Bayard, William J	 	2288
	Anjier, Joseph L	 	8237
	Bombet MD, Leon H	 	9153
	Borak, Rachel	 	3203
	Brewer, Ralph	 	5949
	Bowman, Edwin A	 	3203
	Burroughs MD, Richard	 	16017
	Hirsch, Gary S. & Karen E	 	6864
	Hirsch, Gary S	 	11898
	Weldon, William E	 	15559
	Weldon, William & Cornelia	 	10525
	Newcomer, JR, George C	 	8237
	Cassidy, Laura	 	3661
	Pace, William Robert	 	6407
	CJS Investments	 	2288
	Claiborne, Earl B.	 	10068
	Claiborne, Earl B. & Ethel L.	 	2288
	Head & Neck P/S Plan, Clinic of	 	2746
	Head & Neck Pension Pln, Clinic	 	5949
	Collins, Steven & Eileen	 	2746
	De Fraites, Rebecca Kay	 	1831
	de Jongh, Maria P	 	1831
	De Fraites JR, Emanuel G	 	4576
	de Jongh, Alberto & Maria	 	14644
	Delhaye Children's Tr II	 	5949
	Mayfield, Mary Jo	 	10525
	Dement, Leon D. & Sylvia L.	 	6864
	Delhaye, Mary Field	 	2288
	Dupont, J. Benton	 	10525
	Dupont MD, J. Benton	 	2746
	Dyer, Herbert R.	 	16475
	Phillips, Gary N	 	19220
	Silverberg, Joel D	 	2288
	Trahan III, Victor "Trey"	 	11898

 

	Barry, Mary Kathleen V	 	18305
	Cloud, Louise C	 	5492
	Fazio, Frank L	 	4119
	Ferguson, William F	 	4576
	Mayfield FP, Field	 	5949
	Sanders, Donald Leroy	 	6864
	Fleury, JR, Linton Albert	 	5034
	Gasparrini, Sue D	 	2288
	Gasparrini, William G	 	5949
	Mayfield, Drew Generation Skippi	 	915
	Greco, Leu Anne	 	4576
	Greco TTEE, Cyrus John	 	9153
	Grissom MD, Robert T	 	2288
	Grissom MD, Robert T	 	1373
	Greco, Cyrus John	 	10983
	Haga, D Bruce	 	2288
	Hall MD, Donald Leroy	 	10068
	Kennon JR, Robert F	 	6407
	Harner, James Oliver	 	6407
	Hirsch, Karen Elkind	 	2746
	Haydel, Froisin J.	 	20127
	Haydel, F. Joseph & Frances L.	 	4576
	Mayfield Trust, John D.	 	2288
	Bayard, William J & Peggy G	 	2746
	Bayard, William J & Peggy G	 	1373
	Norman, Joseph R.	 	8695
	Norman, Joseph R. & Susan	 	1373
	BCL Investment Partnership	 	8237
	Kirsch JR, William G	 	3661
	Herad, Khosrow	 	5034
	Trahan III "Trey", Victor F	 	915
	Laville, Anne	 	4576
	Laville, Anne M.	 	3661
	Lee, David M	 	3661
	Lee, J. David	 	9153
	Lockwood, Thomas M.	 	2288
	La. Realtors Assoc LDF	 	4576
	Delhaye Trust, Mary Jo	 	915
	Maestri Jr., Natale A	 	2288
	Mayfield, Lucy R	 	3661
	Mayfield, Mary Jane	 	8695
	Cloyd, William P.	 	10068
	McMillin, Bill	 	6407
	McNeil, Edwin B	 	4576
	Mosley, Guy J & Wanda M	 	5492
	Mosley, Guy J	 	2746
	Mosley, Wanda M	 	3661
	Myres, Betty G	 	4576

2

 

	Myres, Yancey C	 	4119
	Shannon, Keith D	 	3661
	Noland, Ameila M	 	4576
	Ordeneaux, Jerry C.	 	12814
	Poche, Francis Jay	 	1373
	Pollard, Glenda S	 	5949
	Reine MD, Georgia A	 	1831
	Reine, Georgia A	 	16017
	Richey, Anne Q	 	6407
	Richey, Charles A	 	6407
	Richey, Charles A & Anne Q	 	5492
	Coleman & Partners, Robert	 	9153
	Russo III DDS, Camille Joseph	 	5492
	Russo, Camille J & Patricia	 	4576
	Russo III DDS MPP, Camille J	 	8237
	Rucci, Peter J	 	3661
	Schexnayder, Michael C. & Charl	 	2288
	Schexnayder MD, Michael C.	 	5492
	Schucker, Robert Charles	 	15559
	Schwartzberg, Harvey J	 	6407
	Schwartzberg, Harvey J & Betty	 	2288
	Schwartzberg, Ellis J. & Barb	 	5034
	Shannon, Maureen G	 	4576
	Drake, Kathryn M	 	1373
	Cloyd MD, William P.	 	19220
	Solar, Karen Kay	 	2746
	Mayfield Trust, Lucy R.	 	2288
	Steen, Gayle	 	16017
	Collins TTEE, Steven D	 	4576
	Stark, Michael M	 	7322
	Wood, Danny S.	 	1373
	Cavalier, MD, Steven J.	 	10068
	Alvarez, MD, Frank J.	 	9153
	Schwartzberg, MD, Glen	 	7780
	Robin, MD, Richard L.	 	12814
	Roberts, MD, Floyd J.	 	15102
	Melker MD, Merritt "Trey"	 	9153
	Dement, MD, Leon N.	 	17390
	Gladney, MD, William W.	 	9153
	Peairs, MD, Patricia T.	 	3203
	Hargus, MD, Louis Field	 	11441
	Waggenspack, MD, Mark	 	6407
	Silverberg, MD, Joel	 	2288
	Rolfsen, MD, Michael	 	7322
	Seiter, MD, Elizabeth D.	 	8237
	Vicari, MD, Roberta C.	 	4576
	Vath, MD, Richard R.	 	9610
	Silvey, Edgar H.	 	7322

3

 

	Hecker MD, Roger	 	3203
	Earhart MD, Robert N	 	10525
	Vinci, MD, Edmund	 	5492
	Fraser, MD, Warren M.	 	11441
	Thudium, Jr., John F.	 	15102
	Barry, Mary Kathleen	 	3203
	Garcia, O J	 	5949
	Waguespack, Hubert J.	 	12814
	Waguespack, Phillip J.	 	9153
	Wall IV, Williams D	 	4119
	Wall IV, Williams D	 	2746
	Walsh, Robert Eugene	 	1831
	Walsh, Robert & Linda	 	4576
	Williams, John Kelly	 	7322
	Wood, Danny S. & Leah S.	 	2288
	Wood, MD, Danny S.	 	10068
	Bernhard, Jo'An O	 	3661
	Zuckerman, Steven J.	 	4576
	Zuckerman, Steven & Marialden	 	4119
	Allen, Lane	 	5949
	Ashford, Jules	 	10068
	Bradford, Juanita	 	6864
	Ellison, Linda	 	4576
	Gust, Dorothy	 	915
	Gust, Richard	 	5949
	Salter, Barbara	 	4119
	Summers, Steven	 	2746
	Summers, Jane	 	915
	Summers, S & J	 	3203
	

TOTAL:	
 	

1,077,248

4

 
 

Annex B    
    

 
 

Instrument of Accession    
    

        Reference is made to that certain Registration Rights Agreement dated as of May [27], 2003, a copy of which is attached hereto (as amended
and in effect from time to time, the "Registration Rights Agreement"), among iBasis, Inc., a Delaware corporation (the
"Company"), and the Holders (as defined therein). 

        The
undersigned,                              , is the owner or holder of [the Company's 11.5% Senior
Secured Notes due 2005 and/or the Company's warrants to purchase shares of common
stock, par value $0.0001 per share (the "Warrants")] and hereby agrees that, by [his/her/its] execution hereof, the undersigned is a Holder party to the
Registration Rights Agreement and that [he/she/it] is subject to all of the restrictions and conditions applicable to Holders set forth in such Registration Rights Agreement,
and all of the [11.5% Senior Secured Notes due 2005 and Warrants] owned by the undersigned as of the date hereof (and any and all securities of the Company issued in respect
thereof) are subject to all the restrictions and conditions applicable to Registrable Securities as set forth in the Registration Rights Agreement. This Instrument of Accession shall take effect and
shall become a part of said Registration Rights Agreement immediately upon acceptance thereof by the Company. 

        Executed
as of the date set forth below under the laws of the Commonwealth of Massachusetts. 

	

 	
 	

Signature:	

 
	 	 	 	

	

 	
 	

Address:	

 
	 	 	 	

	

 	
 	

 	

	

 	
 	

 	

	

 	
 	

Date:	

 
	 	 	 	

	

Accepted:	
 	

 
	

iBASIS, INC.	
 	

 
	

By:	

 	
 	

 
	 	
	 	 
	

Date:	

 	
 	

 
	 	
	 	 

QuickLinks

Exhibit 10.58

iBASIS, INC. and the HOLDERS listed on Annex A hereto

REGISTRATION RIGHTS AGREEMENT Dated as of May 29, 2003

TABLE OF CONTENTS

Annex A

Holders

Annex B

Instrument of Accession

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