Moscow, Russian Federation — April 4, 2006 — Mobile TeleSystems OJSC (“MTS” — NYSE: MBT), the largest mobile phone operator in Russia and the CIS, announces the completion of the merger of nine subsidiaries into MTS.

In line with MTS’ strategy to improve the Group’s efficiency, the Company has completed the merger of nine of its 100%-owned subsidiaries in Russia. The following subsidiaries were merged into MTS: Gorizont RT, TAIF-TELKOM, MTS-RTK, Sibchallenge, Tomsk Cellular Communications (“TSS”), BM Telecom, Far East Cellular Systems-900 (“FECS-900”), Siberia Cellular Systems-900 (“SCS-900”) and Uraltel.

The merger process was approved by the Extraordinary General Meeting on February 22, 2006 and by the Russian registration authority on March 31, 2006.