Exhibit 99.1

          Robert H. Brumley Joins iBasis Board of Directors

    BURLINGTON, Mass.--(BUSINESS WIRE)--Sept. 20, 2005--iBasis, Inc.
(OTCBB:IBAS), a leader in international long distance, VoIP, and
prepaid calling cards, today announced that Robert H. Brumley has
joined its Board of Directors.
    Mr. Brumley has extensive experience in international
telecommunications, law, and finance. He is president and CEO of
TerraStar Networks, an emerging provider of advanced mobile satellite
services. Prior to joining TerraStar, Mr. Brumley was founder and
managing member of Pegasus Global LLC, an international development
and advisory services firm specializing in technology, capital
formation, and market strategies and solutions for domestic and
international companies. Mr. Brumley has also held executive
management positions at leading telecommunications carriers including
Deutsche Telekom, Bell Atlantic, and Cambrian Communications, a
wholesale metropolitan area network provider. His responsibilities in
those positions included strategic planning and direction, global
business development, and legal affairs.
    Previously, as an international law practitioner, Mr. Brumley
helped clients develop international business relationships in the
fast-growing regions of Central and Eastern Europe, Latin America, and
Asia. As General Counsel of the U.S. Department of Commerce, appointed
by President Reagan, Mr. Brumley was the chief legal officer of the
Department and senior policy advisor to the Secretary of Commerce.
    Mr. Brumley replaces Peter D. Aquino, who has resigned from the
board to focus on his responsibilities as CEO of RCN, a position he
accepted in December 2004.
    "I'm very pleased to have Robert Brumley join our Board, and we
look forward to benefiting from his extensive international
development experience," said Ofer Gneezy, president and CEO of
iBasis. "Also, we're very grateful to Peter Aquino for his
contribution to the company, and we wish him success at RCN."

    About iBasis

    Founded in 1996, iBasis (OTCBB: IBAS) is a leading wholesale
carrier of international long distance telephone calls and a provider
of retail prepaid calling services, including the Pingo(TM) web-based
offering (www.pingo.com) and disposable calling cards, which are sold
through major distributors and available at retail stores throughout
the U.S. iBasis customers include many of the largest
telecommunications carriers in the world, including AT&T, Cable &
Wireless, China Mobile, China Unicom, MCI, Sprint, Skype, and
Telefonica. iBasis carried approximately 5 billion minutes of
international voice over IP (VoIP) traffic in 2004, and is one of the
ten largest carriers of international voice traffic in the world(1).
For four consecutive years service providers named iBasis the best
international wholesale carrier in ATLANTIC-ACM's annual International
Wholesale Carrier Report Card(2). iBasis was also ranked among the
fastest-growing technology companies in New England in the 2002, 2003,
and 2004 Technology Fast 50 programs sponsored by Deloitte & Touche.
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.

    iBasis is a registered mark and Pingo is a trademark of iBasis,
Inc. All other trademarks are the property of their respective owners.

    Except for historical information, all of the expectations,
projections and assumptions contained in the foregoing press release,
including those relating to the company's current expectations
regarding revenue growth, sources of revenue, margin improvement and
future capital expenditures constitute forward-looking statements
under the Private Securities Litigation Reform Act of 1995 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 extent of adoption of the
company's services and the timing and amount of revenue generated by
these services; (ii) fluctuations in the market for and pricing of
these services; and (iii) the other considerations described as "Risk
Factors" in iBasis' most recent Forms 10-K and 10-Q, and the company's
other SEC filings. We have no current intention to update any
forward-looking statements.

    (1)Telegeography 2005 data compared with iBasis 2004 traffic
volume.

    (2)ATLANTIC-ACM International Wholesale Carrier Report Card -
2002, 2003, 2004, & 2005.

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