iBasis Announces Resignation of Michael J. Hughes

D.J. Long, Vice President, Corporate Development

Named Interim Chief Financial Officer

BURLINGTON, MA - June 15, 2001 - iBasis, Inc., (Nasdaq: IBAS) today announced that Michael J. Hughes, Vice President, Finance and Administration and Chief Financial Officer has resigned from iBasis to assume an executive position with an early stage company. D.J. Long, vice president of Corporate Development, has been named the company's Interim Chief Financial Officer. Long has 22 years of financial and managerial experience in high tech mergers and acquisitions and strategic business development, including as senior vice president of Business Development at i2i, Inc., a business-to-business, e-commerce start-up and as director of Business Development at Avid Technology, Inc., a leading provider of digital audio and video tools for information and entertainment applications. Prior to Avid, Long held managerial positions at Lotus Development Corp. and Prime Computer, Inc.

"We'd like to take this opportunity to thank Mike for his service to iBasis," said Ofer Gneezy, president and CEO of iBasis. "Mike joined us when the company had fewer than 20 people and helped us grow into a global leader with more than $60 million in revenue last year and more than $30 million in pro forma revenue in Q1 of 2001. Mike also helped to assemble an experienced finance team, which will provide financial leadership as we continue to move toward our expected profitability in the first quarter of next year. We wish him well in his new endeavor."

"I have truly enjoyed participating in iBasis' phenomenal growth as the company has moved from a start-up to an established services carrier and am very proud of our accomplishments," said Michael J. Hughes. "Together, we raised more than $500 million to finance the iBasis business plan. And now I look forward to re-engaging in the unique opportunities and financing challenges of a start-up. I'd like to extend a special thanks to the iBasis Board and management team as well as to the Finance team and all of my colleagues at iBasis. I wish them continued success."

About iBasis

Founded in 1996, iBasis (Nasdaq: IBAS) is the leader in advanced Internet-based voice communications. iBasis delivers toll quality international voice services and provides the infrastructure for hosted communications solutions, including messaging and speech-enabled content, e-commerce and customer service applications. The company's customers include many of the largest enterprises and carriers in the world, including AT&T, Cable & Wireless, China Mobile, China Unicom, Concert, ExxonMobil, Gannett, H&R Block, Home Shopping Network, Morgan Stanley, NTT, Telstra, Sabre Group, Sprint, Western Union, WorldCom, and Verizon. iBasis' hosted, enhanced service solutions include SpeechPortTM, a scalable, customizable ASP environment for speech-enabled business solutions, VoCore^SM messaging and the IP CallCardTM pre- and post-paid calling card platform. The iBasis Network is the world's largest international Cisco Powered Network for Internet Telephony and the first to receive the Unified Communications-Cisco Powered Network (UC-CPN) designation. iBasis is listed in both the Russell 2000® and Russell 3000® Indexes. The company can be reached at its worldwide headquarters in Burlington, Mass., USA at 781-505-7500 or on the Internet at http://www.ibasis.com .

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Assured Quality Routing and iBasis are registered marks, VoCore is a service mark, The iBasis Network, Internet Central Office, Internet Branch Office, IP CallCard, SpeechPort, IPort, and PriceInteractive are trademarks of iBasis, Inc. or its subsidiaries. Cisco and Cisco Powered Network are registered trademarks of Cisco Systems, 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 new voice-based Internet services and the timing and amount of revenue generated by these services; (ii) fluctuations in the market for and pricing of VoIP services; and (iii) the other considerations described as "Risk Factors" in iBasis' Annual Report on Form 10-K for its fiscal year ended December 31, 2000, and the company's other SEC filings.