Colombia Telecom and Antel Select iBasis for Global Service

Colombian and Uruguayan National Carriers Extend

iBasis VoIP Leadership and Network Footprint in South America

BURLINGTON, MASS. - September 10, 2002 - iBasis, Inc., (Nasdaq: IBAS), the leader in Internet-based voice communications, today announced that Colombia Telecom, the national carrier of Colombia, and Antel, the national carrier of Uruguay, have interconnectied with The iBasis NetworkTM for global service. Colombia Telecom's and Antel's interconnections to iBasis will enable them to route international voice traffic over The iBasis Network and allow iBasis to expand its service in Latin America using the national carriers' extensive networks.

Colombia Telecom and Antel will route their international voice traffic through an iBasis Internet Branch Office (IBO), enabling them to benefit from a low cost, high quality IP-to-IP interconnection to the The iBasis Network. An iBasis IBO comprises VoIP gateways and related interconnection equipment and quality monitoring and management technology. With these agreements iBasis expands its ability to terminate calls in Colombia and Uruguay for its more than 160 carrier customers who include all of the top U.S.-based international carriers. One of the world's 10 largest carriers of international traffic¹, the company was recently ranked by global service providers as the world's #1 international wholesale carrier² and first among international VoIP carriers in network quality.

"iBasis offers us a tremendous opportunity to expand and improve our international service, even while enjoying the cost benefits of the public Internet," said Carmina Amaris, Director of Interconnections for Colombia Telecom. "As a leading provider of voice services throughout North, Central and South America, we wanted to work with a global provider like iBasis that would provide a high quality of service for our customers while expanding our global communications footprint."

"Colombia Telecom and Antel, like many PTTs around the world, are simplifying their international operations by leveraging our many interconnection agreements around the world," said Ofer Gneezy, president and CEO of iBasis, "This enables them to focus on enhancing their domestic business, and at the same time capture the benefits of Internet telephony for their international calls."

iBasis in Latin America

These relationships highlight iBasis' significant market presence in Latin America - a region that is expected to experience a 50% annual growth rate in VoIP traffic through 2006³. Through its more than 40 carrier partners in the region, which include Telefonica, Telecom Argentina, and Orbitel, iBasis is able to provide service to Argentina, Chile, Colombia, Mexico, and Uruguay.

About Colombia Telecom

Colombia Telecom is the largest fixed Telephone Operator in Colombia. Including its 15 regional affiliates, Colombia Telecom has more than 2.7 million installed lines. They are also the largest provider of Long Distance and International Long Distance voice services in Colombia. Their portfolio of services include: Corporate Voice VPNs, Long Distance, Pre-paid, 1- 800 services, Leased Lines, ATM, FR, IP, Internet access (dedicated and dial-up), hosting and collocation.

About Antel

Antel is the largest provider of communications services in Uruguay, with more than 1.2 million installed lines and more than 50% share of the mobile phone service market. Through its Antel Data subsidiary, the company is also the leading provider of internet access in the country.

###