iBasis Announces Date For Fourth Quarter 2007 Financial Results Release and Conference Call

BURLINGTON, Massachusetts – 01/10/2008 – iBasis (NASDAQ: IBAS), a KPN affiliate, today announced that it will report fourth quarter 2007 financial results on Monday, February 4, 2008, after the closing of the stock market. The Company will host a conference call that same day at 5:00 p.m. ET, led by Ofer Gneezy, its President and CEO, to discuss the results, progress on the integration of iBasis and KPN Global Carrier Services, and expectations for 2008.

In the past, iBasis has announced quarterly results before the market opening. The change to an after-market-close release of financial results will enable effective coordination of financial results announcements with Royal KPN N.V., the national carrier of the Netherlands and majority shareholder of iBasis. KPN is scheduled to announce its results on Tuesday, February 5, 2008.

The public is invited to listen to the simultaneous webcast by logging in through the iBasis investor relations website at http://investor.ibasis.com. The webcast is also being distributed through the Thomson StreetEvents Network to both institutional and individual investors. Individual investors can listen to the call at www.fulldisclosure.com, Thomson/CCBN’s individual investor portal, powered by StreetEvents. Institutional investors can access the call via Thomson’s password-protected event management site, StreetEvents (www.streetevents.com).

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 more than 20 billion minutes of international voice traffic in 2006. 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.