iBasis Begins Process to Regain NASDAQ Listing with Preliminary Filing for Reverse Stock Split

Company Builds on Momentum in Revenue, Margin, and Retail Business to Launch Relisting Effort

BURLINGTON, Mass., Dec 15, 2003 -- iBasis, Inc. (OTCBB: IBAS), the leader in Internet-based voice communications, today announced that it has filed a preliminary proxy statement with the SEC that includes a proposal that would give the iBasis board of directors authority to effect a reverse split of iBasis' common stock.

The reverse stock split proposal will be voted on by shareholders at a special meeting to be held February 9, 2004. An affirmative vote by shareholders will permit the iBasis board of directors to choose to effect a reverse stock split of the Company's common stock at a ratio of between one-and-a-half for one (1.5:1) and five for one (5:1). Alternatively, the board may choose not to effect such a split. On a pre-split basis, iBasis currently has 44.8 million common shares outstanding.

The Company is seeking shareholder approval of a possible reverse stock split to increase the per share market price of the Company's common stock for the purpose of achieving compliance with the listing requirements of the NASDAQ SmallCap or National Market. Initial listing requirements for the NASDAQ SmallCap Market include a minimum bid price of $4.00 per share and a market capitalization of $50 million. Initial listing requirements for NASDAQ National Market include a minimum bid price of $5.00 per share and a market capitalization of $75 million. The Company believes that trading on either the SmallCap Market or the National Market may provide a broader market for the Company's common stock and facilitate the use of the Company's common stock in financing transactions.

"We are achieving excellent growth in our wholesale international business and traction in our higher-margin retail prepaid business, and we are making progress towards profitability," said Ofer Gneezy, president and CEO of iBasis. "Our market capitalization crossed over the $50 million minimum required for the NASDAQ SmallCap Market on August 25, 2003 and has remained above that level to date. As of the end of Q3, our debt was under $70 million, down from more than $200 million just two years ago. We accomplished this debt reduction opportunistically, utilizing a variety of cost-efficient approaches. We believe that NASDAQ listing will be instrumental in further deleveraging our balance sheet to the benefit of our investors."

About iBasis

Founded in 1996, iBasis (OTCBB: IBAS) is a leading provider of wholesale international telecommunications services. For the past two years the company has been named by service providers as the best international wholesale carrier in Atlantic-ACM's annual International Wholesale Carrier Report Card¹. iBasis is a preferred provider for many of the largest carriers in the world, including AT&T, Cable & Wireless, China Mobile, China Unicom, MCI, Sprint, Telefonica, Telenor, and Telstra. iBasis has carried more than six billion minutes of international voice traffic over its global Cisco Powered Network™, and is one of the ten largest carriers of international voice traffic in the world². In addition to its wholesale international telecommunications services, iBasis provides retail prepaid calling cards to major distributors, utilizing the international iBasis Network. 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.

The New England Technology Fast 50 program is presented by Deloitte & Touche and Hale and Dorr, in association with the sponsor, Mazonson Inc. In addition, Mass High Tech and Trinity Communications are associated with the program.