iBasis Achieves Additional $12.2 Million Reduction in Original Bond Debt

Company Has Reduced Original $150 Million Debt in 5.75% Notes to $38.2 Million Through Exchanges and Repurchases

BURLINGTON, MASS. - May 29, 2003 - iBasis, Inc. (OTCBB: IBAS), the leader in Internet-based voice communications, today announced that it received a commitment from a group of noteholders to exchange approximately $12.2 million of the Company's 5.75% Convertible Subordinated Notes due 2005, of which approximately $11.8 million was retired today.

Under the terms of the agreement, the noteholders agreed to surrender an aggregate principal amount of approximately $12.2 million of iBasis' outstanding 5.75% Convertible Subordinated Notes in exchange for approximately $6.1 million aggregate principal amount of new 11.5% senior secured notes issued by iBasis and warrants to purchase an aggregate 1,116,605 shares of iBasis common stock. Each warrant will have an initial exercise price of $0.65 per share of Common Stock and a term of five years.

The new Notes, which mature on January 15, 2005, share in a second priority lien on the Company's assets and are subordinated to iBasis' senior debt to Silicon Valley Bank. Inclusive of this bond exchange, the outstanding face amount on the Company's 5.75% Convertible Notes will be $38.2 million, down from its original $150 million aggregate principal amount.

"We are very pleased to have accomplished cashless exchanges that comprise $50.2 million aggregate principal amount of our 5.75% Convertible Subordinated Notes due 2005," said Ofer Gneezy, president and CEO of iBasis. "Through exchanges and repurchases we have now reduced our convertible debt and capital lease debt by approximately $137 million during the past 18 months. These measures, along with our $15 million line of credit, are enabling us to increase shareholder value and enhance our ability to grow the business."

About iBasis

Founded in 1996, iBasis (OTCBB: IBAS) is a leading provider of wholesale international telecommunications services. Named each of the last two years by service providers as the #1 international wholesale carrier in Atlantic-ACM's annual International Wholesale Carrier Report Card, iBasis is a preferred provider for many of the largest carriers in the world. Customers include AT&T, Cable & Wireless, China Mobile, China Unicom, Sprint, Telefonica, Telenor, Telstra, and WorldCom. The company's global VoIP infrastructure, The iBasis NetworkTM, is the world's largest international Cisco Powered NetworkTM for Internet Telephony. Based on its revenue growth from 1997 through 2001, iBasis was ranked the #8 fastest-growing technology company in North America and the #1 fastest-growing technology company in New England in the Technology Fast 500 national program 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.

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Assured Quality Routing, iBasis, and ConnectPoint are registered marks, The iBasis Network, Internet Central Office, Internet Branch Office, and IP CallCard are trademarks of iBasis, Inc. 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 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.