Moscow, Russian Federation – Mobile TeleSystems OJSC (“MTS” – NYSE: MBT), the leading telecommunications operator in Russia and the CIS, announces that Moody`s Investor Service has upgraded MTS’s senior unsecured issuer rating from Ba2 to Baa3 with a stable outlook. This represents a two-notch upgrade and classifies MTS as investment grade.

Visit Moody’s 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