Moscow, Russian Federation – June 28, 2007 – Mobile Telesystems OJSC (“MTS” - NYSE: MBT), the largest mobile phone operator in Russia and the CIS, announces that it has acquired the remaining 26% stake in Uzdunrobita.

MTS has purchased an additional 26% stake in Uzdunrobita, the leading mobile operator in Uzbekistan, from a private investor for $250.0 million in cash. Previously MTS owned 74% of Uzdunrobita; as a result of this transaction, MTS’ ownership has increased to a full 100%.

MTS first acquired a 74% stake in Uzdunrobita for $121.0 million in August 2004. As announced at the time of the acquisition, MTS also signed a three-year put and call agreement with the remaining shareholder of Uzdunrobita to purchase the outstanding 26% stake. An amendment to the original option agreement, announced in August 2006, extended the exercise period of the put option to July 14, 2008. Following the put option exercise, an independent valuation opinion of Uzdunrobita for the purpose of determining the option exercise price was provided by Renaissance Capital.

MTS President and CEO, Mr. Leonid Melamed, commented, “Our partnership in Uzbekistan has enabled us to develop a leading position in a market that continues to grow in visibility and importance within MTS Group. Our customers in Uzbekistan make use of innovative products, enjoy high-quality service and affordable tariffs. The full consolidation of Uzdunrobita, the quality of the organization we have built and the development of a 3G standard allow us to capitalize on the full potential of this market for both the customers and shareholders of MTS.”

Uzdunrobita is the largest mobile phone operator in Uzbekistan with approximately 1.85 million subscribers as of May 31, 2007. Uzdunrobita holds licenses for GSM and 3G services for the entire country.