iBasis Posts Record Traffic Volume and Revenue For Fourth Quarter and Full Year 1999

Company Carries More Than 156 Million Minutes in 1999; Sequential Quarterly Revenue Up 31.5%

Burlington, Mass.-February 10, 2000-iBasis, Inc., (Nasdaq: IBAS) today announced results for the fourth quarter and the full year ended December 31, 1999. Fourth quarter revenue was $7.60 million, an increase of 31.5% compared with third quarter revenue of $5.78 million. Similarly, fourth quarter 1999 revenue increased by 440.8% over fourth quarter 1998 revenue of $1.41 million.

Net loss for the fourth quarter 1999 was $7.55 million, or a pro forma net loss of $0.27 per basic and diluted share based on 27.99 million weighted average shares outstanding. This net loss compares to a third quarter 1999 net loss of $6.28 million, or a pro forma loss of $0.27 per basic and diluted share based on 22.94 million pro forma weighted average shares outstanding.

For the full year 1999, revenue totaled $19.42 million, an increase of nearly ten times the full year 1998 revenue of $1.98 million. Net loss for the full year 1999 was $21.09 million compared to a net loss of $5.73 million in 1998. Pro forma basic and diluted net loss per share for the full year 1999 was $0.97 based on 21.79 million weighted average shares outstanding. This net loss compares to pro forma 1998 basic and diluted net loss per share of $0.33 based on 17.36 million weighted average shares outstanding.

Pro forma basic and diluted net loss per share and weighted average shares outstanding in 1998 and 1999 were calculated assuming all preferred stock had converted into common stock as of the date of original issuance.

"I'm very pleased with our continued significant growth in each of our key business indicators: revenue, minutes and overseas lines," said Ofer Gneezy, president and chief executive officer of iBasis. "We carried more than 156 million minutes in 1999 for major carriers, including tier one US carriers, providing further evidence of the unsurpassed quality of our IP network, which is the world's largest international Cisco Powered NetworkTM for Internet telephony. In addition, our recent joint announcement with Cisco that we are teaming up to deliver IP-based VoCore greatly expands our business opportunities. This is further evidence of the strength of our business model, which enables us to quickly and easily deliver advanced services on top of our global network infrastructure."

Key Indicators
Minutes of use rose to 63.8 million minutes in the fourth quarter of 1999, an increase of 42.6% over the third quarter's 44.8 million minutes and compared to 9.1 million minutes in the fourth quarter of 1998. For the full year, minutes totaled 156.5 million compared to 12.1 million minutes of use in 1998, a 1,193.7% increase.

The iBasis Network™ footprint was significantly expanded in the fourth quarter and the year. The Company's total overseas lines were 3,220 at the end of the fourth quarter of 1999, up from 2,398 at the end of the third quarter. Overseas lines were 510 at December 31, 1998. The company believes that the number of overseas lines accurately represents the capacity of its global network.

The iBasis Network™ consists of high-capacity, carrier-class Internet Central Offices (ICOs) as well as Internet Branch Offices (IBOs) located throughout Asia, Africa, Europe, the Middle East and the Americas and can terminate phone traffic in virtually every country in the world. During the fourth quarter of 1999, iBasis expanded into the European markets, deploying initial ICOs in London and Frankfurt. The company has announced plans to quadruple the number of ICOs in its global network to a total of 20 by the end of 2000.

Operational Milestones
During 1999, the company broadly deployed the SS7 signaling protocol (Signaling System 7) over its global network infrastructure. SS7 is used by tier one carriers to speed call set-up, reduce post-dial delay and enhance overall service quality.

During the fourth quarter of 1999, iBasis introduced the industry's first Internet telephony hosting services. With iBasis Internet Telephony HostingTM, service providers have access to comprehensive, customizable, outsourced solutions that enable them to quickly begin offering voice, fax, prepaid calling, and other value-added VoIP services, including VoCore with minimal upfront investment.

Subsequent to quarter and year-end, iBasis announced the industry's first Service Level Agreement (SLA) for Voice-over-Internet-Protocol (VoIP), which guarantees call completion rates equal to or better than those provided by alternative networks, including the Public Switched Telephone Network. As a result of iBasis' ability to provide toll quality service, the highest service quality obtainable, 10 of the top 12 US international carriers, including tier one providers, are iBasis customers.

Also subsequent to the quarter and year-end, iBasis and Cisco Systems announced they are joining forces to deliver carrier-class, IP-based, VoCore services. iBasis will deploy in its network Cisco's VoCore (UC) solution, called uOneTM, The Cisco Open Network Exchange. uOne uses the open Internet Protocol (IP) standard to unify communications methods that were previously disjointed, including e-mail, fax machines, voice mail systems, cellular phones, and the Web. uOne enables users to initiate and return voice calls and send and receive faxes, e-mail, and voice messages- independent of location, time or device.

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 NetworkTM is the world's largest international Cisco Powered Network for Internet Telephony. iBasis customers include 10 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' preliminary prospectuses dated February 10, 2000, and the company's other SEC filings.

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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.