Ad hoc notice

Ruling on the Tax Review Decision for the Years 2005 and 2006

December 26, 2008

Moscow, Russian Federation – Mobile TeleSystems OJSC (“MTS” – NYSE: MBT), the largest mobile phone operator in Russia and the CIS announces that the Moscow Arbitrage Court ruled against the tax claims for the years 2005 and 2006 in the amount of RUR 0.98 billion.

The tax claims against MTS were the result of a tax inspection of the Company’s financial statements for the years 2005 and 2006 that amounted to RUR 1.13 billion (including approximately RUR 144 million in fines and penalties), which is approx. $40 million(1) (including approx. $5 million in fines and penalties).

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For further information, please contact:

Mobile TeleSystems, Moscow

Investor Relations

Tel: +7 495 223 2025

E-mail: ir@mts.ru

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Mobile TeleSystems OJSC (“MTS”) is the largest mobile phone operator in Russia and the CIS. Together with its subsidiaries, the Company services over 89.68 million subscribers. The regions of Russia, as well as Armenia, Belarus, Turkmenistan, Ukraine, and Uzbekistan, in which MTS and its associates and subsidiaries are licensed to provide GSM services, have a total population of more than 230 million. Since June 2000, MTS’ Level 3 ADRs have been listed on the New York Stock Exchange (ticker symbol MBT). Additional information about MTS can be found on MTS’ website at www.mtsgsm.com.

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Some of the information in this press release may contain projections or other forward-looking statements regarding future events or the future financial performance of MTS, as defined in the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. You can identify forward looking statements by terms such as “expect,” “believe,” “anticipate,” “estimate,” “intend,” “will,” “could,” “may” or “might,” and the negative of such terms or other similar expressions.  We wish to caution you that these statements are only predictions and that actual events or results may differ materially. We do not intend to update these statements to reflect events and circumstances occurring after the date hereof or to reflect the occurrence of unanticipated events. We refer you to the documents MTS files from time to time with the U.S. Securities and Exchange Commission, specifically the Company’s most recent Form 20-F. These documents contain and identify important factors, including those contained in the section captioned “Risk Factors” that could cause the actual results to differ materially from those contained in our projections or forward-looking statements, including, among others, potential fluctuations in quarterly results, our competitive environment, dependence on new service development and tariff structures, rapid technological and market change, acquisition strategy, risks associated with telecommunications infrastructure, risks associated with operating in Russia and the CIS, volatility of stock price, financial risk management and future growth subject to risks..

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(1) According to the Russian Central Bank exchange rate of 28.3359 RUR/$ as of December 24, 2008.

MOBILE TELESYSTEMS OJSC

By:

/s/ Mikhail Shamolin

Name:

 Mikhail Shamolin

Title:

  CEO

Date:  December 26, 2008