Mobile TeleSystems OJSC (MBT) is a provider of mobile cellular communications services in the Russian Federation and Ukraine, employing technology based primarily on Global System for Mobile Communications (GSM). In addition to standard voice services, the Company offers its subscribers value-added services, including voice mail, short message service (SMS), general packet radio service (GPRS), various SMS- and GPRS-based information and entertainment services (including multimedia messaging service), and data and fax transmission. It also offers its subscribers the ability to roam automatically throughout Europe and in much of the rest of the world. MBT operates in the Russian Federation, its principal market, under the commercial names Mobile TeleSystems, MTS and Jeans. It operates in Ukraine through its subsidiary, Ukrainian Mobile Communications. Through joint venture Mobile TeleSystems LLC, MBT operates in Belarus. At year-end 2003, the Company's subscriber base was 16.7 million.