Moscow, Russian Federation – February 20, 2007 – Mobile Telesystems OJSC (“MTS” - NYSE: MBT), the largest mobile phone operator in Russia and the CIS, announces that the Moscow Arbitrage Court ruled in favor of MTS in its counter-claim against the Federal tax service rejecting tax claims for the years 2003 and 2004 in the amount of RUR 1.216 billion.

The Moscow Arbitrage Court ruled that tax claims in the amount of RUR 1.216 billion were void. The tax claims against MTS were the result of a tax inspection of the Company’s financial statements for the years 2003 and 2004 that amounted to RUR 1.284 billion (including approximately RUR 308 million in fines and penalties).