3U Telecom Interconnects with iBasis for International Telecom Services

Leading European `Call-by-Call' Carrier Expands iBasis Presence

BURLINGTON, MASS. - June 18, 2003 - iBasis, Inc. (OTCBB: IBAS), the leader in Internet-based voice communications, today announced that 3U TELECOM, a provider of retail long distance services has interconnected with The iBasis NetworkTM for international telecommunications services. By interconnecting with iBasis, 3U will be able to route international voice traffic over The iBasis Network, as well as complete calls for iBasis over 3U's advanced fiber optic network in North America and Europe.

3U is one of many fast-growing providers of telecommunication services that allow customers to utilize "call-by-call" carrier selection to maximize potential savings on local, as well as domestic and international long distance calls. 3U customers in seven countries - the U.S., Germany, France, Italy, Switzerland, Austria, and the Netherlands - choose 3U by dialing a designated four or five digit prefix before placing their call.

"iBasis and 3U share the same commitment to quality service," said Udo Graul, CEO, 3U TELECOM. "Taking advantage of the iBasis global network for international call completion will help us to expand our global business efficiently."

"Call-by-call carrier selection, or `dial-around', is a fast growing segment of the retail telecommunications industry in which the strength of the carrier's brand is highly dependent on the quality of every call," said Ofer Gneezy, president and CEO of iBasis. "By interconnecting with iBasis, 3U is taking advantage of the quality of service we provide as well as cost-efficient access to our global footprint to deliver reliable, high quality service to their retail customers."

About 3U Telecom
Headquartered in Marburg (Germany), 3U Telecom was founded in 1997 to provide high quality long distance phone service for residential and business customers at low prices. Using the increasingly popular open call-by-call procedure and 3U's advanced fibre optic network, customers in the U.S. Germany, Switzerland, Italy, France, Austria, and the Netherlands select 3U for domestic and international long distance calls to fixed and mobile phones around the world. In November 1999 3U Telecom completed a successful initial public offering and is listed on the Frankfurt stock exchange.

About iBasis

Founded in 1996, iBasis (OTCBB: IBAS) is a leading provider of wholesale international telecommunications services. The company was named by service providers for two consecutive years 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, Sprint, Telefonica, Telenor, Telstra, and MCI. iBasis has carried more than six billion minutes of international voice traffic over its global Cisco Powered NetworkTM, which has also been the highest rated wholesale VoIP network for two years in a row². 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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