March 2010

Mobile TeleSystems Announces Financial Results for the Fourth Quarter and Full Year Ended December 31, 2009

Moscow, Russian Federation — Mobile TeleSystems OJSC («MTS» — NYSE: MBT), the leading telecommunications provider in Russia and the CIS, today announces its unaudited US GAAP financial results for the three months and full year ended December 31, 2009.

Fourth Quarter and Full Year 2009 Financial Results Announcement and Conference Call

The management of Mobile TeleSystems (MTS) will be holding a conference call to discuss the Company’s Fourth Quarter and Full Year 2009 Financial and Operating Results on Wednesday, March 31, 2010.

Ad Hoc Notice

Moscow, Russian Federation – Mobile TeleSystems OJSC (the “Company” or “MTS” – NYSE: MBT), the largest mobile phone operator in Russia and the CIS, announces that “COMSTAR – United TeleSystems” JSC (“Comstar” - LSE: CMST), a majority-owned subsidiary of MTS, has released its fourth quarter and full year 2009 financial and operating results earlier today.

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