Moscow, Russian Federation – Mobile TeleSystems OJSC (“MTS” – NYSE: MBT), the leading telecommunications provider in Russia and the CIS, announces that MTS’ Voluntary Tender Offer (“VTO”) to COMSTAR – United TeleSystems JSC (“Comstar” – LSE: CMST) shareholders will close at 17.00 EST on September 8, 2010 for Global Depositary Receipt (“GDR”) holders in advance of the closing on September 21, 2010 for all other Comstar shareholders.

For further information on the mechanics of taking part in the VTO and if you have questions about tendering your shares, please contact Georgeson, the leading shareholder communications firm, which MTS has retained to provide support and assistance for the VTO process. Both Comstar GDR and Ordinary shareholders should contact Georgeson using the contact details provided below.

Notes to Editors:

MTS submitted documentation to Comstar on July 13, 2010 regarding MTS’ VTO to acquire up to 37,614,678 Comstar ordinary shares that MTS or its affiliates do not already own for RUR 220.0 per Comstar share. The number of ordinary shares is equivalent to 9.0% of Comstar’s issued share capital, and includes shares underlying Comstar GDRs.

Goldman Sachs International is acting as financial advisor to MTS and Latham & Watkins LLP is acting as legal advisor to MTS.

Documentation regarding the MTS Voluntary Tender Offer to acquire Comstar shares is available at https://www.mtsgsm.com/merger/.