Zimbabwe Telecom Selects iBasis for Internet Telephony

Interconnection Agreement Extends Global Footprint for Zimbabwe's National Carrier; Expands iBasis Services in Fast-Growing African Market

BURLINGTON, MA - March 26, 2001 - iBasis, Inc., (Nasdaq: IBAS), the leader in advanced Internet-based voice communications, today announced that Zimbabwe Posts & Telecommunications Corporation (Zimbabwe PTC), the national carrier of Zimbabwe, working together with iBasis' local partner, IP Africa, a regional communications services provider, has chosen the iBasis Network^TM for Internet telephony services. The agreement enables Zimbabwe PTC to efficiently expand its international services by routing traffic over the iBasis Network. In addition, iBasis, by connecting to Zimbabwe PTC's extensive domestic and regional network, will be able to broaden its footprint in this fast-growing African telecommunications market.

Connecting to The iBasis Network, a global Internet telephony infrastructure with more than 426 Points of Presence in more than 45 countries, will help Zimbabwe PTC further expand and improve the quality of international service for its customers.

"Zimbabwe PTC is committed to improving the quality and reach of our international services by leveraging the latest technologies and strongest global partners as we move into the 21^st century," said Mrs. Nomsa Jowah, Manager of Data Transmission at Zimbabwe Telecom. "With iBasis, the provider of choice for the world's largest carriers, we knew we could be assured of service quality indistinguishable from the PSTN, at much lower cost."

"iBasis is very successful in delivering cost-effective communications services that improve quality and reduce costs for developing countries," said Ofer Gneezy, president and CEO of iBasis. "Throughout Asia and Latin America, for example, we have seen that Internet telephony offers an economically compelling alternative for carriers seeking to expand their communications infrastructure. Zimbabwe PTC's decision to connect to our global network for international service reflects the consensus of both Tier 1 carriers and those in the developing world that the path to better communications is carrier-class VoIP."

The iBasis Network: Carrier-Class VoIP

The iBasis Network is a robust, global platform for the delivery of IP-based communications services, including wholesale, phone-to-phone VoIP and enhanced services, such as unified communications and speech-enabled business solutions. The company's global network delivers IP-based voice services using Internet Telephony equipment from Cisco Systems deployed in large, carrier-class switching and application hosting facilities called Internet Central Offices^TM, strategically located in Amsterdam, Cambridge (Mass.), Frankfurt, Hong Kong, London, Los Angeles, Miami, New York, Paris, Singapore, Stockholm, Sydney, Tokyo, and Toronto. The network also comprises numerous smaller points of presence called Internet Branch Offices^TM, which play an important role in connecting providers to iBasis services. With this global infrastructure in more than 45 countries and through its relationships with other communications providers, iBasis can provide IP-based voice services virtually anywhere in the world.

iBasis is the only provider 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 Centers (NOC) in Burlington, Mass., USA and Hong Kong, the nerve centers of The iBasis Network, engineers continuously monitor the global circuit-switched (PSTN) and packet-switched (IP) networks to ensure the highest quality of service to customers worldwide.

About iBasis
Founded in 1996, iBasis (Nasdaq: IBAS) is the leader in advanced Internet-based voice communications. iBasis delivers toll quality international voice services and provides the infrastructure for hosted communications solutions, including unified communications and speech-enabled content, e-commerce and customer service applications. The company's customers include many of the largest enterprises and carriers in the world, including AT&T, Cable & Wireless, China Mobile, China Unicom, Concert, ExxonMobil, Gannett, H&R Block, Home Shopping Network, Morgan Stanley, NTT, Telstra, Sabre Group, Sprint, Western Union, WorldCom, and Verizon. iBasis' hosted, enhanced service solutions include SpeechPort^TM, a scalable, customizable platform for speech-enabled business solutions, VoCore^SM unified communications and the IP CallCardTM pre- and post-paid calling card platform. The iBasis Network is the world's largest international Cisco Powered Network for Internet Telephony and the first to receive the Unified Communications-Cisco Powered Network (UC-CPN) designation. iBasis is listed in both the Russell 2000® and Russell 3000® Indexes. 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 .

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Assured Quality Routing and AQR are registered trademarks, VoCore is a service mark and iBasis, The iBasis Network, Internet Central Office, Internet Branch Office, IP CallCard, SpeechPort, IPort, and PriceInteractive are trademarks of iBasis, Inc. or its subsidiaries. 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 new voice-based Internet services and the timing and amount of revenue generated by these services; (ii) fluctuations in the market for and pricing of VoIP services; and (iii) the other considerations described as "Risk Factors" in iBasis' Annual Report on Form 10-K for its fiscal year ended December 31, 2000, and the company's other SEC filings.