Vietnam's Largest Telecommunications Carrier Selects iBasis to Expand Global Service

Vietnam Telecom International, Leading Provider in World's Third Fastest-Growing Telecommunications Market to Expand International Reach with VoIP Leader;

Agreement to Extend iBasis Network Footprint into Vietnam

BURLINGTON, MA -March 18, 2002 -iBasis, Inc., (Nasdaq: IBAS), the leader in Internet-based voice communications, today announced that Vietnam's leading telecommunications provider, Vietnam Telecom International (VTI), is interconnecting with The iBasis NetworkTM. A subsidiary of the state-owned Vietnam Posts and Telecommunications Corporation (VNPT), VTI will expand its global service by leveraging iBasis' Tier 1 quality VoIP service - recently ranked by global service providers as the #1 international wholesale carrier¹. VTI's interconnection to iBasis will enable VTI to route its international voice traffic over The iBasis Network and allow iBasis to terminate international calls into Vietnam on VTI's infrastructure. According to the International Telecommunications Union, Vietnam is third fastest-growing telecommunications market in the world.

"As the largest carrier in Vietnam, a rapidly-growing nation of more than 78 million people, we sought the best and most efficient global voice service available. With their extensive experience in major Asian markets and Tier 1 reliability, iBasis was our clear choice," said Mr. Nguyen Huu Khanh, deputy managing director at VTI. "Our interconnection to The iBasis Network will enable us to expand our global reach while maintaining affordable, high quality service."

"We are very excited at the prospects for our relationship with VTI, the telecommunications leader in a very fast-growing market," said Ofer Gneezy, president and CEO of iBasis. "VTI is taking the lead in introducing to its customers advanced services such as VoIP, which lower communications costs and expand economic growth. We look forward to providing our high quality international service to the people of Vietnam. And since Vietnam is a relatively high revenue per minute destination, as we ramp up our service with VTI over the next few months, we may see an increase of as much as 1¢ in our average revenue per minute (ARPM) network-wide."

Vietnam: A Large and Rapidly Expanding Market

As Vietnam has expanded its infrastructure and trade relationships and become integrated with the global economy, domestic teledensity (number of phones per 100 inhabitants) increased 17-fold² and voice traffic volumes into that country have grown dramatically. According to Telegeography 2002, global voice traffic into Vietnam grew 37% from 1999 to 2000 (the most recent period for which statistics are available). During that same period, voice traffic from the United States to Vietnam grew by 56% - placing that route within the top 20 US-outbound calling destinations.

About Vietnam Telecom International (VTI)

Founded in 1990, Vietnam Telecom International (VTI) is an exclusive 100% state-owned subsidiary of Vietnam Posts and Telecommunications (VNPT). VTI's current services include international telephony, fax and telex; Home Country Direct (HCD); international teleconferencing; IPLC; VSAT; Immarsat; international television transmission; international video conferencing; and Voice-over-IP international telephony and related services. VTI can be found on the Internet at www.vti.com.vn .

About iBasis

Founded in 1996, iBasis (Nasdaq: IBAS) is the leader in Internet-based voice communications. iBasis delivers toll quality international voice services and provides the infrastructure for hosted communications solutions, including 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, Telefonica, Telenor, Telstra, Sabre Group, Sprint, Western Union, and WorldCom. iBasis' hosted, enhanced service solutions include SpeechPortTM, a scalable, customizable ASP environment for speech-enabled business solutions. The iBasis Network is the world's largest international Cisco Powered Network for Internet Telephony. iBasis is listed in both the Russell 2000® and Russell 3000® Indexes. The company can be reached at its worldwide headquarters in Burlington, Massachusetts, USA at 781-505-7500 or on the Internet at www.ibasis.com .

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Assured Quality Routing and iBasis are registered marks, The iBasis Network, Internet Central Office, Internet Branch Office, IP CallCard and SpeechPort 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 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. We have no current intention to update any forward-looking statements.

According to industry analyst publication TeleGeography 2002, teledensity in Vietnam increased 17-fold from 1990-1999 (the latest period for which statistics are available).