Exhibit 99.1

         iBasis Announces Delay in Filing First Quarter 10-Q

               Update on Nasdaq Stock Market Proceedings


    BURLINGTON, Mass.--(BUSINESS WIRE)--May 16, 2007--iBasis (NASDAQ:
IBAS), the global VoIP company, today announced that it was unable to
file its first quarter 2007 Quarterly Report on Form 10-Q for the
quarter ended March 31, 2007 by the required filing date of May 10,
2007.

    As previously announced, a Special Committee of independent
directors, appointed by the Board of Directors of iBasis, Inc. (the
"Company"), has conducted an internal investigation relating to stock
options granted to the employees of the Company, the timing of such
grants and their related accounting and tax treatment. On October 20,
2006, the Company disclosed that the Special Committee had concluded
that the appropriate measurement dates for determining the accounting
treatment of certain stock option grants differ from the measurement
dates used by the Company in preparing its financial statements. As a
result, the Company currently expects to record additional non-cash
charges in the range of $10 million to $20 million for stock-based
compensation over the period from fiscal 2000 through June 30, 2006
and will accordingly restate its financial statements for that period.

    The Company has not yet finalized the amount to be recorded in any
specific period, nor has the Company finally determined the tax
consequences and any related liabilities that may result from these
matters. The amounts to be recorded are subject to review and audit by
the Company's independent registered public accounting firm. As a
result of the foregoing, the Company was unable to file its Quarterly
Report on Form 10-Q for the quarter ended March 31, 2007 by the
required filing date of May 10, 2007 without unreasonable effort or
expense. The Company does not anticipate that it will be able to file
its Form 10-Q on or before the fifth calendar day following the
prescribed due date, in accordance with Rule 12b-25. For the same
reasons, the Company was also unable to file its Quarterly Report on
Form 10-Q for the quarter ended September 30, 2006 by the required
filing date of November 9, 2006 or its Annual Report on Form 10-K for
the year ended December 31, 2006 by the required filing date of March
16, 2007. The Company is focused on resolving these issues as quickly
as possible and plans to file its quarterly and annual reports and
restatements as soon as practicable.

    Update on Nasdaq Stock Market Proceedings

    As previously announced, on March 12, 2007, the Company was
informed by The Nasdaq Stock Market that the Nasdaq Listing and
Hearing Review Council has stayed the April 26, 2007 deadline for the
delisting of the Company's securities, pending further review by the
Listing Council. The Listing Council further informed the Company that
it may submit in writing additional information for the Listing
Council's consideration by June 1, 2007.

    On May 16, 2007, the Company received an additional Nasdaq staff
determination letter indicating that the Company's failure to file its
Form 10-Q for the quarter ended March 31, 2007 on May 10, 2007 could
serve as an additional basis for the delisting of the Company's
securities from The Nasdaq Stock Market, under Nasdaq Marketplace Rule
4310(c)(14) and informing the Company that it may submit in writing
additional information for the Listing Council's consideration by May
22, 2007.

    There can be no assurance that the outcome of the Listing
Council's review will be favorable to the Company, that the Listing
Council will not lift the stay, or that the Company's securities will
remain listed on The Nasdaq Stock Market.

    About iBasis

    Founded in 1996, iBasis (NASDAQ: IBAS) is a leading wholesale
carrier of international long distance telephone calls and a provider
of retail prepaid calling services, including the Pingo(R) web-based
offering (www.pingo.com) and disposable calling cards that are sold
through major distributors and available at retail stores throughout
the U.S. iBasis customers include many of the largest
telecommunications carriers, including AT&T, Verizon, China Mobile,
China Unicom, IDT, Qwest, Skype, Telecom Italia, and Telefonica.
iBasis carried more than 11 billion minutes of international voice
over IP (VoIP) traffic in 2006, and is one of the largest carriers of
international voice traffic in the world(1). The Company can be
reached at its worldwide headquarters in Burlington, Massachusetts,
USA at 781-505-7500 or on the Internet at www.ibasis.com.

    1. Based on Telegeography 2007 and iBasis actual 2006 traffic.

    iBasis and Pingo are registered marks, The iBasis Network and the
global VoIP company are trademarks of iBasis, Inc. All other
trademarks are the property of their respective owners.

    Except for historical information, all of the expectations, plans
and assumptions contained in the foregoing press release constitute
forward-looking statements under Section 21E of the Securities
Exchange Act of 1934 and involve risks and uncertainties. Important
factors that could cause actual results to differ materially from such
forward-looking statements include, but are not limited to, (i) the
Company's ability to execute its business plan; (ii) the extent of
adoption of the Company's services and the timing and amount of
revenue and gross profit generated by these services; (iii)
fluctuations in the market for and pricing of these services; (iv) the
other factors described in the Company's Quarterly Report on Form 10-Q
for its most recently completed fiscal quarter and Annual Report on
Form 10-K for its most recently completed fiscal year all of which are
available at http://www.sec.gov. Such forward-looking statements are
only as of the date they are made, and we have no current intention to
update any forward-looking statements.

    CONTACT: iBasis, Inc.
             Media:
             Chris Ward, +1-781-505-7557
             cward@ibasis.net
             or
             Investors:
             Richard Tennant, +1-781-505-7409
             ir@ibasis.net