Ad Hoc Notice

June 18, 2009

Moscow, Russian Federation — Mobile TeleSystems OJSC (“MTS” — NYSE: MBT), the largest mobile phone operator in Russia and the CIS, announces that today it has received approval from the Federal Anti-Monopoly Service (FAS) to acquire up to 100% of Comstar UTS, based on its application filed on May 22, 2009.

If realized, the transaction would create an integrated telecommunications operator in Russia and the CIS and accelerate the development of integrated and broadband communications services throughout our regions of operation.

As MTS announced on May 22, 2009, because a potential transaction would involve related parties, MTS’ Board of Directors has established a Special Committee of its three Independent Directors to oversee the transaction process and decide whether to recommend the acquisition of Comstar UTS to the full Board of Directors.  Independent financial and legal advisors, hired through a tender process and reporting to the Committee, will provide fairness opinions, legal analyses and additional advisory services to the Committee members.

JSFC Sistema (LSE: SSA), the largest diversified public financial corporation in Russia and the CIS, owns nearly 50.9% of Comstar UTS and 53.1% of MTS.

No decision has yet been made with respect to the size or structure of any potential transaction.

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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 93.98 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.

MOBILE TELESYSTEMS OJSC

By:

/s/ Mikhail Shamolin

Name:

Mikhail Shamolin

Title:

CEO

Date:   June 18, 2009