iBasis and MTS Ukraine Interconnect to Exchange Mobile International Voice Traffic

Leading Ukrainian Mobile Operator Selects iBasis for International Mobile Services

BURLINGTON, Massachusetts – 03/31/2008 – iBasis (NASDAQ: IBAS), a KPN affiliate, today announced that MTS Ukraine, one of the largest mobile operators in Ukraine, has interconnected with The iBasis Network for international voice services. The interconnection with iBasis enables MTS Ukraine to route its international mobile voice traffic over The iBasis Network and expands iBasis’ ability to complete mobile calls in the country.

In selecting iBasis, MTS Ukraine is taking advantage of iBasis’ comprehensive voice products portfolio, which was enhanced by the company’s acquisition of KPN Global Carrier Service in October 2007. MTS Ukraine is utilizing iBasis’ International Premium Service (IPS), with its high quality and enhanced feature set for mobile operators. The synergy between KPN Global Carrier Services and iBasis enables the combined company to provide mobile operators important mobile features such as guaranteed CLI and global roaming.

Intense competition in mobile and in the international wholesale market are driving operators worldwide to find more competitive solutions based on quality, efficiency, scale and profitability. Mobile operators are also looking for future-proof solutions that will help them to compete in the new arena of converged technologies and services.

“Mobile operators are increasingly recognizing the importance of an effective strategy for moving to IP and working with global partners that can help them to increase efficiency in their international business,” said Ofer Gneezy, president and CEO of iBasis. “With approximately 24 billion minutes of annual international voice traffic, we are now one of the three largest carriers of international phone calls in the world 1. We have enhanced our global product portfolio to provide mobile operators with compelling solutions for their international business. Our proven resources and expertise in IP combined with KPN Global Carriers Services’ mobile expertise is enhancing the growth, efficiency and profitability of leading mobile network operators such as MTS Ukraine.”

“Instant scalable access to international infrastructure allows us to grow our traffic while continuing to offer world standard services to our mobile subscribers,” said Andrey Dubovskov, CEO of MTS Ukraine. “As one of the top mobile network operators in Europe, it is important for us to work with leading providers in different telecom branches, including IP-telephony. iBasis has the proven high quality and industry-leading expertise we need.”

Like many telecommunications markets, growth in Ukraine continues to be fuelled by mobile expansion. By the end of February 2008, there were more than 55 million mobile subscribers in Ukraine, with mobile penetration over 118 %. 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.

Based on KPN Global Carrier Services established business in mobile services, iBasis has relationships with more than 100 mobile operators, as well as international traffic from KPN’s Dutch, German, and Belgian operations. In addition to a reliable international routing product portfolio, iBasis offers a comprehensive portfolio of value-added services for Mobile Operators, and MVNOs. Called Mobile Matrix, the mobile data services portfolio offers a wide range of value added mobile services that can be hosted in iBasis infrastructure.

About MTS Ukraine

The MTS Ukraine network covers more than 95 % of Ukraine and 99 % of the population. The company serves around 20 million subscribers. MTS Ukraine owns licenses for providing mobile (GSM 900/1800, CDMA-450), fixed, toll, and long-distance communication services, and provides international roaming services on five continents. The company reported $1.49 billion revenues in 2006. For more information, visit web site: www.mts.com.ua.

About iBasis

Founded in 1996, iBasis (NASDAQ: IBAS) is a leading wholesale carrier of international long distance telephone calls and a provider of retail prepaid calling services and enhanced services for mobile operators. iBasis customers include KPN, KPN Mobile, E-Plus, BASE, and many other large telecommunications carriers such as AT&T, Verizon, Vodafone, China Mobile, China Unicom, IDT, Qwest, Skype, Telecom Italia, Telefonica, and Yahoo. In October 2007, iBasis acquired KPN Global Carrier Services to create one of the three largest carriers of international voice traffic in the world, and KPN became a majority stockholder of iBasis. On a pro forma basis, the combined company carried approximately 24 billion minutes of international voice traffic in 2007. The Company can be reached at its worldwide headquarters in Burlington, Mass., USA at +1 781-505-7500 or on the Internet atwww.ibasis.com.