

	iBasis and Telstra Establish Interconnect For Internet Telephony Australia's Premier Carrier To Exchange Internet Telephony Traffic With The iBasis Network; Agreement Extends iBasis Global Footprint Across Asia-Pacific and Other Key Regions Burlington, Mass.-May 10, 2000-iBasis, Inc., the leader in advanced Internet-based communications, today announced that is has signed an agreement to exchange Internet Telephony traffic with Telstra, Australia's premier, full-service, top-tier global carrier. Under the terms of the agreement, Telstra will be able to route international Internet telephony traffic over the iBasis Network™, the world's largest international Cisco Powered Network for Internet telephony. iBasis will be able to terminate international Internet telephony traffic from its network onto Telstra's global telecommunications network that spans over 200 international destinations in the Asia-Pacific region, Americas, Europe, and the Middle East. "Telstra's decision to exchange international traffic with iBasis will allow both companies to better serve the international service provider market," said Ofer Gneezy, president and CEO of iBasis, Inc. "Our agreement with Telstra is not only a vote of confidence in our tier one VoIP services, but also significantly expands our network's footprint into the important business centers of the Asia-Pacific region and other key global hubs." iBasis in Asia The relationship with tier one carrier Telstra adds to those already established by iBasis with more than 70 international carriers, including 11 of the top 12 US international carriers. In the Asia-Pacific region, iBasis has partnerships with China Unicom, NTT in Japan, The Communications Authority of Thailand, Dacom in Korea, and other regional carriers. The iBasis Network™ The iBasis Network™ is the world's largest international Cisco Powered Network™ (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 Routing™ (AQR™) 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 Telstra Corporation Limited Telstra is Australia's premier communications carrier and is a world-class, fully integrated, full service provider across wireline, ADSL, HFC, satellite and digital wireless networks and platforms. It is Australia's leading ISP, has the most highly accessed family of Internet portals and sites and provides entertainment and multimedia content over its broadband network and through its Pay-TV joint venture. Telstra owns and operates one of the most technologically advanced networks, offering end-to-end solutions ranging from broadband, IP, mobile and intelligent network services, to voice and data network hubs, call centers, and advanced multimedia and e-commerce applications. It has business operations in 19 countries in the Americas, UK/Europe/Middle East and Asia-Pacific regions. Telstra is a top tier global carrier with fiscal 1998/99 revenue of A$18.2 billion (approx. US$11.6 billion). For more information, visit Telstra on the Internet at www.telstra.com. 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™ 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. ### iBasis, The iBasis Network and Assured Quality Routing are registered trademarks of iBasis, Inc. Cisco and Cisco Powered Network are registered trademarks of Cisco Systems, Inc