Moscow, Russian Federation – Mobile TeleSystems OJSC (“MTS” – NYSE: MBT), the leading telecommunications operator in Russia and the CIS, announces that Standard & Poor's Ratings Services has downgraded the Company’s long-term foreign and local currency corporate credit rating from 'BBB-' to 'BB+' following the downgrade of the Russia’s sovereign rating from ‘BBB-‘ to ‘BB+’. The outlook on the MTS’s foreign currency rating and the local currency rating remains negative. Ratings on the Company's senior unsecured debt were downgraded from 'BBB-' to 'BB+'.

Standard & Poor's Ratings Services noted in the release that it maintained the assessment of MTS’ standalone credit risk profile at ‘BBB-‘, supported by a ‘satisfactory’ business risk profile and a ‘modest’ financial risk profile.

Visit Standard & Poor's website to view the full release.

For further information, please contact in Moscow:

Joshua B. Tulgan
Director, Corporate Finance & Investor Relations
Mobile TeleSystems OJSC
Tel: +7 495 223 2025
E-mail: ir@mts.ru