April 2003

MTS to Acquire an Additional 26% Stake in UMC

Moscow — April 30, 2003 — Mobile TeleSystems OJSC (“MTS” — NYSE: MBT), the largest mobile phone operator in Russia and Central and Eastern Europe1 today announces that it has decided to exercise an option agreement with Ukrtelecom to acquire an additional 26% stake in Ukrainian Mobile Communications (UMC).

Start of “Formula-1 SMS-forecast” game

From April 25 on the threshold of the 5-th round of Formula-1 World Championship Grand Prix of Spain a new SMS-game starts for Royal racing fans.

2003 World Ice Hockey Championship — on-line SMS-digest

Hot information from ice arenas of Finland is offered to you every day on your mobile phone! Be the first to find out the Championship’s highlights even on the May holiday. You don’t need now to wait for a new issue of a sport newspaper or TV sport newscast.

MTS Reports Preliminary Unaudited Revenue Numbers for 2002

Moscow, April 29, 2003. Mobile TeleSystems OJSC (“MTS” — NYSE: MBT), the largest mobile phone operator in Russia and Central and Eastern Europe , today announced preliminary unaudited revenue and subscriber numbers for the fourth quarter and the full year 2002.

Mobile Magic of the VIA "Gra" group

“MTS-Extra” company is the exclusive MTS representative in terms of setting up partner system, providing information services on the basis of interactive interaction technology (IVR) and holds prize drawing on the occasion of a new album released by the splendid Slav girls of the VIA “Gra” group!

Trade mark MTS operates now in Rostov-na-Donu

From April 23 the MTS’ subsidiary Dontelecom in the Rostov region starts providing its services under the trade mark MTS.

Long-distance calls to Bashkortostan become cheaper

From April 22, 2003 Bashkortostan Republic is integrated into “Zone of reduced long-distance tariffs. Europe”.

Bashkortostan Republic: MTS low roaming tariffs apply now in 54 Russia’s regions

From April 22, 2003 MTS low tariffs for intranet roaming apply in the coverage zone of “BM Telecom“ (Bashkortostan Republic). From now on MTS reduced roaming tariffs are available in 54 Russia’s regions and Belarus. Among GSM operators in Russia this is the largest network of “saving trips“.

Win a trip! Guess the last hero!

MTS’ partner MTS-Extra company jointly with VID TV company holds the unique campaign “Guess the last hero”!

Your phone can now rings as a bird

In terms of the “Pictures and ring tones” service at the site at: www.jippii.ru a new category of ring tones “Spring bird’s songs” is added.

Welcome to Formula-1 site

Dear users, fans of Formula 1 racing! MTS offers you a new site at www.f1.mts.ru (available in Russian).

Become monsters of show business!

MTS jointly with “CrossMedia Solutions” company offers to you a new WAP-game of multiple usage “Star maker” !

From April 20 “Number storage for the winter” becomes obsolete

MTS reminds to its users with stored phone numbers for the winter that from April 20, 2003 the “Number storage for the winter” service will become obsolete.

Calls to Orenburg came down

MTS is always striving to offer both high quality of mobile services and new more beneficial tariff plans. The 14-th April is the launch date of the MTS network in the Orenburg region. From April 14:

MTS launches its network in the Orenburg region

On April 14, 2003 MTS launches its network in the Orenburg region. We are delighted to congratulate both inhabitants of the Orenburg region, who can now enjoy quality and reliability of the MTS network, and all MTS users — from now on low roaming tariffs apply in 53 Russia’s regions and in Belarus. This coverage zone- the largest among GSM operators in Russia- presents a large network of “saving tours“.

Win a trip for two to Milan!

Buy Siemens C55 or Siemens A50 at MTS sales offices and get a chance to win a trip for two to Milan for the week-end!

“JEANS-Tonic” is the tariff plan for young and active people!

On April 2 MTS announces a new tariff plan in the JEANS tariff group! The JEANS-Tonic tariff plan is designed for young and active people who can enjoy both working hard and having a good time!

MTS Acquires a Controlling Stake in TAIF-TELKOM

Kazan, Moscow, Russian Federation — April 2, 2003 — Mobile TeleSystems OJSC (“MTS” — NYSE: MBT), the largest mobile phone operator in Russia and Central and Eastern Europe, today announces that it has signed agreements to acquire a controlling stake in TAIF-TELKOM OJSC.

Contact investor relations:

+ 7 495 223 20 25 ir@mts.ru

MTS Investor Relations
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