

	iBasis and Belle Systems Create Next Generation Platform for Advanced VoIP Services Leaders in Internet telephony and Billing and Management Solutions Announce Strategic Relationship Burlington, Mass.—January 25, 2000—iBasis, Inc., (NASDAQ: IBAS), the leader in international Internet telephony and Belle Systems A/S, a leading provider of IP billing, provisioning and management solutions for the on-line and telecommunications industries, today announced that their companies have formed a strategic relationship that will create the next generation platform for advanced, value-added voice-over-Internet-Protocol (VoIP) services. As part of this agreement, iBasis will deploy Belle Systems' Internet Management System (IMS) for management and billing of its voice and fax over IP services. Integration of Belle Systems' billing and management technologies with the iBasis NetworkTM, the world's largest international Cisco Powered NetworkTM for Internet telephony, will provide iBasis and its customers with an enhanced network infrastructure that enables more efficient management and delivery of value-added VoIP services, including comprehensive pre- and post-paid services and unified messaging. "If the initial opportunity in Internet telephony was focused on rate arbitrage, the next wave of growth in Internet telephony will be driven by advanced services," said Matthew Kristin, CIO of iBasis. "Our strategic relationship with Belle Systems, a global leader in billing and management solutions, will be central to our ability to continue to lead the market in delivering this new generation of IP telephony services to market." "With our robust, proven billing and management technologies, Belle Systems is working closely with iBasis to create a future-proofed network infrastructure that raises the bar for Internet telephony," said Hasse Rasmussen, chief executive officer for Belle Systems. "And because of our mutual strategic relationship with Cisco, we can ensure that our integrated platform remains at the cutting edge of Internet communications." iBasis to Deploy Belle Systems' Internet Management Service (IMS) iBasis selected Belle Systems as its strategic partner for billing and management following a comprehensive multi-vendor evaluation and review of available technologies. iBasis' initial deployment involves Belle Systems' Internet Management Service (IMS), a comprehensive IP service management and billing solution with the ability to manage and account for all the elements of Internet telephony service - from provisioning and deployment through to mediation, rating and billing - all within a single platform. Using IMS, iBasis network administrators can easily define and efficiently manage users via IP addresses, user names, addresses, departments or payment method. IMS also enables iBasis Network administrators to manage customers by service-type. By combining user and service profiles, iBasis Network administrators can construct common user groups with which they can associate rating schemes. These user/service profiles are also used to authenticate and manage access to the iBasis Network and its services, as well as to automate mediation, billing and collection. Based on the Oracle platform and operating on all leading UNIX hardware systems, IMS is a fault-tolerant, distributed system, consisting of a Master Database, Application Server and RADIUS Servers. The product supports a variety of different rating methods including time, volume, geographical location, and pre-paid card services, providing a flexible, highly customizable solution. About Belle Systems A/S Belle Systems A/S is a leading global software producer specializing in advanced IP service provisioning, management and billing systems for telcos, Internet service providers (ISPs), leased-line operators, cable TV operators and corporate enterprises. The company has been providing management solutions for the on-line and telecommunications market since 1984, and has completed installations at a number of large telecommunications companies and Internet service providers. Belle Systems is a privately held company with investment funding from Internet-working market leader Cisco Systems, and IT venture capitalists, Index Ventures, Vertex Management and General Atlantic Partners. Headquartered in Holbaek, Denmark and with additional offices in Singapore and the UK. Belle Systems employs more than 150 people worldwide. Belle Systems is a member Cisco Systems Inc.'s New World Ecosystem programme and has strategic development and commercial relationships with IT industry leaders, such as Hewlett-Packard, Oracle, Sun Microsystems, Groupe Bull, Unisys and ICL. More information on Belle Systems is available at http://www.bellesystems.com About iBasis Founded in 1996, iBasis (NASDAQ: IBAS) is the global leader in international Internet telephony. iBasis uniquely combines a superior technology platform, premium Internet bandwidth and proprietary Assured Quality Routing� (AQR) software to deliver toll quality Internet telephony services to tier one carriers and other international service providers. The iBasis Network�, a global, high-capacity Internet communications network, is the world's largest international Cisco Powered NetworkTM for Internet Telephony. The company can be reached at its worldwide headquarters in Burlington, Massachusetts, USA at 781-505-7500 or on the Internet at www.ibasis.net. iBasis has a long-standing strategic relationship with Cisco, as an Alliance Partner, an Ecosystem Partner and one of only 21 Cisco Service Provider Global Accounts. 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 the company's prospectus dated November 9, 1999, and the company's other SEC filings. ### iBasis, iBasis Internet Telephony Hosting, 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. All other trademarks are the property of their respective owners.