iBasis Named Fastest Growing Technology Company in New England

Extraordinary Five-Year Growth Rate Earns Company Third Consecutive # 1 Ranking in Deloitte & Touche "Fast 50" and "Rising Stars" Program

BURLINGTON, MASS. - September 23, 2002 - iBasis, Inc., (Nasdaq: IBAS), the leader in Internet-based voice communications, today announced that it received the #1 ranking as New England's fastest growing technology company in Deloitte & Touche's prestigious "Technology Fast 50" Program for New England. The annual Technology Fast 50 program is a ranking of the 50 fastest growing technology companies in the area. Fast 50 rankings are based on the percentage of growth in fiscal year revenues from 1997-2001 (five-year period).

"With close to 9,000 technology companies, New England is second only to Silicon Valley in the concentration of high tech businesses, so we're very proud to be ranked #1," said Ofer Gneezy, president and CEO of iBasis. "While the telecommunications sector is under great pressure today, it's gratifying to see our employees recognized for the tremendous growth they have achieved over the past five years."

iBasis increased its revenues more than 105,000 percent from 1997 to 2001, resulting in its #1 ranking overall in the Fast 50 for New England. The average increase in revenues among companies who made the Fast 50 for this region was 5,390 percent. iBasis has received a #1 ranking from the Technology Fast 50 program for three consecutive years. The company was ranked the #1 "Rising Star" in 2001 and 2000. This is the first year iBasis has qualified for the Fast 50 ranking.

Technology Fast 50 Criteria

To qualify for the New England Technology Fast 50, companies must meet the following criteria:

· Be a technology company, specifically defined as a company that owns proprietary technology, which contributes to a significant portion of the company's operating revenues (e.g., using other companies' technology in a unique way does not qualify) or devotes a high percentage of effort to research and development of technology.

· Be in business a minimum of five years with 1997 revenues of at least $50,000 and 2001 revenues of at least $1,000,000.

· Be a public or private company headquartered in the following New England states: MA, ME, NH, RI or VT. Subsidiaries and divisions are not eligible unless they have some public ownership and are separately traded.

Winners of the 20 regional Technology Fast 50 programs in the United States and Canada are automatically entered in the Deloitte & Touche Technology Fast 500 program, which ranks North America's top 500 fastest growing technology companies. For more information on the Deloitte & Touche Fast 50 or Fast 500 programs, visit www.fast500.com.

About iBasis

Founded in 1996, iBasis (Nasdaq: IBAS) is a leading provider of wholesale international telecommunications services to large carriers and other service providers worldwide. Named by other carriers as the #1 international wholesale carrier in Atlantic-ACM's 2002 International Wholesale Carrier Report Card, iBasis is a preferred provider of international voice services for many of the largest carriers in the world, including AT&T, Cable & Wireless, China Mobile, China Unicom, Concert, Sprint, Telefonica, Telenor, Telstra, and WorldCom. The company's global VoIP infrastructure, The iBasis Network, spans more than 85 on-net countries and 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.com.

The New England Technology Fast 50 program is presented by Deloitte & Touche and Hale and Dorr, in association with the sponsor, Mazonson Inc. In addition, Mass High Tech and Trinity Communications are associated with the program.

About Deloitte & Touche

Deloitte & Touche, one of the nation's leading professional services firms, provides assurance and advisory, tax, and management consulting services through nearly 30,000 people in more than 100 U.S. cities. The firm is dedicated to helping its clients and its people excel. Known as an employer of choice for innovative human resources programs, Deloitte & Touche has been recognized as one of the "100 Best Companies to Work For in America" by Fortune magazine for five consecutive years. Deloitte & Touche refers to Deloitte & Touche LLP and related entities. Deloitte & Touche is the US national practice of Deloitte Touche Tohmatsu. Deloitte Touche Tohmatsu is a Swiss Verein, and each of its national practices is a separate and independent legal entity. For more information, please visit Deloitte & Touche's web site at www.deloitte.com/us. For more information on the Technology Fast 50 and Fast 500 programs, please visit www.fast50.com.

Hale and Dorr LLP

Hale and Dorr, a leading technology law firm, is nationally and internationally recognized for its expertise in venture capital, initial public offerings, intellectual property and securities and intellectual property litigation. We represent clients in numerous sectors including telecommunications, software, electronics, life sciences and medical devices. The firm's full-service practice also includes tax, commercial, labor and employment, real estate, environmental, government and regulatory affairs and private client services, and a strong commitment to public service dating from our founding more than eighty years ago. Hale and Dorr has nearly 500 lawyers with offices in Boston, New York, Princeton, Reston, Waltham and Washington and joint venture offices in London, Munich and Oxford. For more information please visit our website at http://www.haledorr.com/.

About Mazonson, LLC

Founded in 1935, Mazonson, LLC delivers comprehensive, innovative insurance solutions for individuals and businesses including Directors' and Officers' Liability, Global Business Protection and Employee Benefits. Mazonson's unique team concept in servicing clients combines business acumen, domain experience and a comprehensive knowledge of insurance products.
 
Mass High Tech

Mass High Tech, the Journal of New England Technology, is a weekly newspaper that covers the companies, individuals and issues involved in the commercialization of technology in the six-state region.

Trinity Communications

Headquartered in Boston, Trinity Communications is an independent, employee-owned company that provides integrated marketing communications services to clients in the financial services, life sciences, technology, professional services, and nonprofit sectors.

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Assured Quality Routing and iBasis are registered marks, The iBasis Network, Internet Central Office, Internet Branch Office, ConnectPoint Global Access, and IP CallCard are 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.

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 services and the timing and amount of revenue generated by these services; (ii) fluctuations in the market for and pricing of these services; (iii) potential inability of the company to maintain its NASDAQ listing; and (iv) the other considerations described as "Risk Factors" in iBasis' Annual Report on Form 10-K for its fiscal year ended December 31, 2001, and the company's other SEC filings. We have no current intention to update any forward-looking statements.