May 2000

Mobile TeleSystems OJSC Files F1 Registration Statement with U.S Securities and Exchange Commission

A Leading Russian Mobile Cellular Telephone Services Provider Expects to Launch Initial Public Offering. Moscow (May 25, 2000) — Mobile TeleSystems OJSC (“MTS”), a provider of mobile telephone services in Russia, announced today that it intends to launch an Initial Public Offering of 15,010,612 American Depositary Shares (ADSs), each representing twenty shares of common stock of MTS. The offering is expected to take place at the end of June 2000 and will be made to the public in the United States and in private placements in other global markets.

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