iBasis Interconnects with Kyivstar, Largest Mobile Operator in Ukraine, for Global Voice Services

BURLINGTON, MA - February 26, 2007 - iBasis, Inc. (NASDAQ: IBAS), the global VoIP company™,otoday announced that Kyivstar, the leading mobile operator in Ukraine, has interconnected with The iBasis Network™ for international voice services. The interconnection with iBasis enables Kyivstar to route international voice traffic over The iBasis Network, the leading global VoIP network, and expands iBasis' ability to complete mobile calls to Ukraine.

iBasis delivers improved call completion rates and longer average call duration, which help to increase average revenue per user for its mobile operator customers. Kyivstar is leveraging iBasis' advanced international routing portfolio, including its PremiumCertified™ service, which certifies higher route quality and stability.

"The migration of international voice traffic to mobile networks is one of the major trends in global telecommunications today," said Ofer Gneezy, president and CEO of iBasis. "We are very pleased to add Kyivstar to our growing mobile footprint and to have them utilizing our leading VoIP network for their international traffic. Our proven resources and expertise in VoIP are enhancing the growth, efficiency and profitability of leading mobile network operators such as Kyivstar."

By interconnecting their mobile network with The iBasis Network, Kyivstar is able to enhance its margins and revenue growth from inbound and outbound international traffic associated with their rapidly growing national network. Also, using the iBasis DirectVoIP™ service enables Kyivstar to add capacity and new destinations quickly and cost-efficiently.

"As the leading mobile network operator in Ukraine, serving more than half the citizens of Ukraine, it is important for us to focus on offering competitive prices, high quality, and reliability and to take advantage of the benefits that VoIP affords to connect to the rest of the world," said Zhanna Revnova, head of Corporate Affairs of Kyivstar. "The benefits of VoIP, including the instant scalable access to a high quality, low-cost international infrastructure, allow us to grow our international traffic with very competitive rates while continuing to offer high quality of service to our mobile subscribers."

Like many telecommunications markets, growth in Ukraine is fuelled by mobile expansion and VoIP migration. Ukraine's mobile penetration at the end of 2006 was 104 % (by using sim-cards), up from 41% just one year earlier. To continue growth and profitability, mobile operators are increasingly focusing on expanding lifetime revenue and profit per customer, and mastering a more competitive market situation.

iBasis CEO to Address Regional Challenges at Moscow Conference

Mr. Ofer Gneezy, president and CEO of iBasis, will discuss key drivers of the continuing growth in international Voice-over-IP and its impact on regional and global communications as part of his keynote address at The Telecom World Russia & CIS Conference, to be held February 27 through March 1 at the Renaissance Moscow Hotel. Mr Gneezy's presentation, which will begin at 9:40 a.m. local time on March 1, will discuss the strategic factors behind the continuing penetration of VoIP in the region. He will also participate in a panel discussion on managing next generation networks and delivering service assurance for new IP services.

Ukraine is one of the top Eastern Europe VoIP traffic destinations and one of the fastest growing VoIP termination markets, growing 64% in 2004 according to Telegeography. iBasis carries approximately 18 % of all international voice traffic to the top CIS VoIP countries - Russia & Ukraine.

About Kyivstar

The leading national mobile communications operator, Kyivstar provides services for more than 22 million subscribers (as of February 1, 2007). Kyivstar's network covers territories representing 99% of the population, including all the cities and towns, more than 28,000 rural settlements, all main national and regional roads, and most of the sea and river shores of Ukraine. Kyivstar provides GPRS services all over its coverage area in Ukraine. Also, the company provides international GPRS-roaming services in 95 countries in the networks of 163 foreign operators. In total for contract subscribers Kyivstar provides roaming services in the networks of 322 foreign operators in 171 countries on 5 continents. Kyivstar provides the Ukrainian people with modern telecommunication technologies at affordable prices.

About iBasis

Founded in 1996, iBasis (NASDAQ: IBAS - News) is a leading wholesale carrier of international long distance telephone calls and a provider of retail prepaid calling services, including the Pingo® web-based offering (www.pingo.com) and disposable calling cards that are sold through major distributors and available at retail stores throughout the U.S. iBasis customers include many of the largest telecommunications carriers, including AT&T, Verizon, China Mobile, China Unicom, IDT, Qwest, Skype, Telecom Italia, and Telefonica. iBasis carried more than 11 billion minutes of international voice over IP (VoIP) traffic in 2006, and is one of the largest carriers of international voice traffic in the world¹. 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.