Moscow, Russian Federation – Mobile TeleSystems OJSC (“MTS” – NYSE: MBT), the leading telecommunications provider in Russia and the CIS, announces that it has today submitted documentation to COMSTAR – United TeleSystems JSC (“Comstar” - LSE: CMST), a leading supplier of integrated telecommunication solutions in Russia and the CIS, regarding the MTS Voluntary Tender Offer (“VTO”) to acquire up to 37,614,678 Comstar ordinary shares that MTS does not already own for RUR 220.0 per Comstar share. The number of ordinary shares is equivalent to 9.0% of Comstar’s issued share capital, and includes shares underlying Comstar Global Depositary Receipts (“GDR”s). The launch of the VTO follows the announcement on June 25, 2010 that the Boards of Directors of MTS and Comstar had approved and recommended the merger of MTS and Comstar. The VTO documentation was then filed with the Federal Service for Financial Markets (“FSFM”), which has now completed its statutory review. MTS currently owns 61.97% of Comstar, or 64.03% when excluding treasury shares, and consolidates Comstar in its financial results.

As announced on June 25, 2010, the implied VTO price per Comstar GDR of USD 7.16  represents a 13.1% premium to the three month volume-weighted average trading price of the Comstar GDR on the London Stock Exchange up to the close of trading on June 22, 2010.

The Comstar Board of Directors will now review the VTO documentation and decide upon its recommendation to Comstar shareholders regarding the VTO. Comstar will then deliver the documentation, together with its Board of Directors’ recommendation, to Comstar ordinary shareholders and, in the case of Comstar GDR holders, via Deutsche Bank (the depositary bank for Comstar’s GDR facility). Comstar shareholders who subscribe to the VTO will receive a pro rata cash allocation in the event of over-subscription. The VTO period commences from the moment Comstar received the voluntary offer and will remain open until the end of day on September 21, 2010.

MTS has sufficient available cash, cash equivalents and undrawn financing commitments to purchase the shares in the VTO and has further received a bank guarantee in this respect from Sberbank, as required by the applicable rules regarding VTOs.

Mikhail Shamolin, President and Chief Executive Officer of MTS, commented: “The VTO is part of the overall transaction to merge Comstar into MTS, and we believe that the VTO provides Comstar minority shareholders with an attractive liquidity opportunity at a premium to the average historic trading price of Comstar stock”.

“The merger will create the largest integrated telecommunications provider in Russia and the CIS, and we believe that the full integration will accelerate the delivery of our ‘3i’ strategic goal of realizing growth through increasing customer value by providing our customers with a broad, innovative and bundled offering of mobile and fixed line telephony, high-speed broadband internet access and television services. Not only is this expected to further enhance our competitive position, but it is also expected to streamline our common business processes and further optimize our combined operating and capital expenditure programmes.”

Goldman Sachs International is acting as financial advisor to MTS and Latham & Watkins LLP is acting as legal advisor to MTS.

Documentation regarding the MTS Voluntary Tender Offer to acquire Comstar shares is available here: https://www.mtsgsm.com/merger/.