

	iBasis is First to Guarantee Quality of Service For Voice over IP Company's Proprietary AQR™ Technology Ensures Industry's Highest Level of Quality, Backs First Internet Telephony Service Level Agreement Burlington, Mass.-January 19, 2000-iBasis, Inc., the leader in Internet-based communications for international service providers, today announced the industry's first Service Level Agreement (SLA) for Internet telephony. The iBasis Service Level Agreement for international termination services guarantees customers sending calls over the iBasis Network™ call completion rates equivalent to or better than those provided by alternative networks, including the Public Switched Telephone Network (PSTN). The call completion rate, known in the telecommunications industry as the Answer Seizure Ratio (ASR), represents the percentage of calls out of all attempts that are successfully completed. The higher the ASR, the more reliable the network and the more billable calls that result for a carrier. This unprecedented Service Level Agreement for Internet telephony is made possible by iBasis' proprietary Assured Quality RoutingTM (AQRTM) technology, which is used to monitor call completion rates as well as other indicators of service quality. "By offering the telecommunications industry's first Service Level Agreement for voice over the Internet, iBasis has established itself as the leader in a soon-to-be burgeoning industry, " said Michael J. Mahoney, chairman and chief executive officer of Viatel, Inc., among the world's fastest-growing, integrated providers of telecommunications services. "The Company's unique ability to guarantee quality for VoIP was central to our decision to partner with iBasis." "In the rapidly growing Internet telephony industry, iBasis has built a robust worldwide network that reliably delivers toll quality service," said Judy Reed Smith, CEO of Atlantic ACM, a leading telecommunications analyst firm. "By introducing the first service level agreement that guarantees quality of service for voice over IP, iBasis has taken an important step in moving Internet telephony into tier one carrier class territory." "At iBasis, we have always sought to separate ourselves from the herd by focusing on meeting the volume and quality requirements of the world's largest carriers," said Ofer Gneezy, president and CEO of iBasis. "Our service level guarantee proves that iBasis' Internet telephony can not only match traditional service quality, but in certain critical characteristics, it can surpass it." The Keys to Quality: The iBasis Network and Assured Quality RoutingTM The iBasis Network is the world's largest international Cisco Powered NetworkTM (CPNTM) for Internet telephony. Combining advanced technology with world-class IP and telephony engineering expertise, iBasis has built the world's first global network that guarantees toll quality voice and fax service. Toll quality is the telecommunications industry term for the highest level of service quality obtainable. The ability to deliver toll quality is a pre-requisite for carrying tier one carrier voice and fax traffic. The iBasis Network is optimized to deliver low latency and packet loss, high voice quality, no echo, high call completion and low post-dial delay-resulting in call quality equal to or better than that achievable over traditional PSTN lines. 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 using the latest network management tools and the company's AQR technology to ensure the highest quality of service to customers worldwide. IBasis' AQR is employed to dynamically reroute traffic from the Internet to the public switched telephone network (PSTN) as necessary to ensure a seamless, high quality of service. About Viatel Viatel, Inc. is a facilities-based, integrated provider of telecommunications services. Founded in 1991, Viatel is a publicly held company, traded on the NASDAQ stock exchange (ticker symbol: VYTL). Viatel delivers a broad array of competitively priced voice and data services to a variety of end-users, including individual consumers, businesses and carriers in more than 230 countries and territories worldwide. It also provides high-speed, high-capacity, high-quality bandwidth to companies, carriers and Internet service providers. Viatel is a licensed provider of telecommunications services in Belgium, France, Germany, Ireland, Italy, The Netherlands, Spain, Switzerland and the United Kingdom. Viatel currently operates one of the largest pan-European networks, with international gateways in New York and London and network points of interconnection in over 78 European cities. Viatel has invested more than $700 million to date in the development, construction and operation of the Circe Pan-European Network, - an 8,700 route kilometers, state-of-the-art, cross-border, fiber-optic network linking over 40 cities in Western Europe. Phases One and Two of the Circe Network -- over 3,000 kilometers linking London in the United Kingdom; Amsterdam and Rotterdam in The Netherlands; Brussels and Antwerp in Belgium; Paris, Amiens, Nancy and Strasbourg in France; and Dusseldorf, Frankfurt and Mannheim in Germany - are currently in commercial service. 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. 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' 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.