iBasis Expands European Presence, Securing Interconnection Agreement with Leading Russian Provider Sovintel

International Service Agreement Extends Reach of Sovintel's Next-Generation Communications Services; Provides iBasis Network Access to Sovintel's Extensive Footprint in Russia

BURLINGTON, Mass. - June 19, 2000-- iBasis, Inc., (Nasdaq: IBAS), the leader in advanced Internet-based communications, today announced that the company has signed an interconnection agreement with Sovintel, the leading alternative communications service provider in Russia. Under the terms of the agreement, Sovintel will be able to route Internet telephony and fax traffic over the iBasis Network™, the world's largest international Cisco Powered Network for Internet telephony. Additionally, iBasis will be able to terminate international Internet telephony traffic from its global network onto Sovintel's fiber optic digital network in Moscow and St. Petersburg.

"Sovintel has a commitment to quality that has enabled them to become an important player in the Russian telecommunications market," said Ofer Gneezy, President and CEO of iBasis, Inc. "The agreement with Sovintel will provide our customers direct, reliable connections to the important business centers of Moscow and St. Petersburg, the two cities that have become the hubs for Russian international commerce."

"iBasis is a proven global provider for many of the world's largest carriers," said Alexander Vinogradov, General Director of Sovintel. "I am sure that our co-operation with iBasis will complement the high quality of service our customers have come to expect. By connecting to iBasis, we can efficiently extend the reach of our international services. Our success in the Russian market has been achieved because of our reliable and dynamic partners; that's why we are confident of success through our partnership with iBasis."

The iBasis Network 
The iBasis Network is the world's largest international Cisco Powered NetworkTM (CPN) for Internet telephony. iBasis is the only Internet telephony carrier that guarantees service quality by offering the industry's first Service Level Agreement (SLA) for VoIP (Voice-over-Internet-Protocol). The key to maintaining the high level of quality required by the world's largest carriers is the company's proven, proprietary Assured Quality RoutingTM (AQRTM) technology. At the company's 24 x 7 Network Operations Center (NOC), the nerve center of the iBasis Network, located at iBasis' global headquarters in Burlington, Massachusetts, USA, engineers continuously monitor the global circuit-switched (PSTN) and packet-switched (IP) networks to ensure the highest quality of service to customers worldwide. iBasis has a long-standing strategic relationship with Cisco Systems, as an alliance partner, an ecosystem partner, and one of only 21 Cisco service provider global accounts.

About Sovintel 
Founded in 1990, Sovintel is a Russian-American joint venture that has rapidly grown from a young start-up into the leading independent communications provider in Russia. Sovintel is jointly owned by the Russian national carrier, Rostelecom, and the American company, Golden Telecom (Nasdaq: GLDN). Sovintel provides advanced voice, data, IP and video telecommunications services based on its own fiber optic SDH network. In addition to being one of the largest carriers of voice traffic in Russia, Sovintel offers a full range of communications services to large corporate and multinational companies and operates the largest commercial call center in Russia. 

More information about Sovintel can be found on the Internet at www.sovintel.ru.

About iBasis 
Founded in 1996, iBasis (Nasdaq:IBAS) is the leader in advanced Internet-based communications. iBasis has built the world's first global IP network that delivers toll quality voice and fax service and other advanced hosted communications solutions, including VoCore, to global tier one carriers and other service providers. The iBasis Network (TM) is the world's largest international Cisco Powered Network for Internet telephony. More than 70 international carriers are iBasis customers, including 11 of the top 12 US international carriers. The company can be reached at its worldwide headquarters in Burlington, Mass., USA at 781-505-7500 or on the Internet at www.ibasis.net.

Except for historical information, all of the expectations, projections and assumptions contained in the foregoing press release 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, the considerations described as ``Risk Factors'' in iBasis' prospectuses dated March 9, 2000, and the company's other SEC filings.

Assured Quality Routing is a registered trademark and iBasis and The iBasis Network are trademarks of iBasis, Inc. Cisco and Cisco Powered Network are registered trademarks of Cisco Systems, Inc.