December 2003

MTS Increases its Ownership in Siberian Cellular Systems — 900 to 88,5%

Moscow, Russian Federation — December 29, 2003 — Mobile TeleSystems OJSC (“MTS” — NYSE: MBT), Russia’s largest mobile phone operator in terms of subscribers, has acquired an additional 7.5% of Siberian Cellular Systems — 900. As a result of this transaction, MTS’ ownership in the company increases to 88.5%.

MTS congratulates winners of SMS-Olympiad!

On December 19, 2003 at 5pm Moscow time it was announced the winner of the First Russian SMS-Olympiad held by "Mobile TeleSystems" and SPN Digital company. The winner is Ivan Davydov from Rostov-na-Donu who was awarded with the super prize - Toyota Corolla.

Tariff reduction of MTS services

From January 1, 2004 due to cancel of 5% sales tax (article 4, Federal Law as of November 27, 2001, № 148-FL) and VAT off from 20% to 18% (point 11, article 1, Federal Law as of July 7, 2003, №117-FL) tariffs for cellular services as well as cost of equipment and accessories in MTS sales offices will be reduced.

Reduction of tariffs for national roaming

From January 1, 2004 tariffs for national roaming are substantially reduced due to the achieved agreements with a number of Russian cellular operators as well as to cancel of 5% sales tax and VAT decrease from 20% to 18%.

CLI for Voice mail

Ladies and gentlemen! News for all users of voice/fax mail (VFM)! You can now identify the calling number from which you received a message in your Voice mail. You can see this number in the new SMS notification text of VFM and VFM automatic system will notify you about it when retrieving.

TV-Chat on TV-3

New opportunity to tell about yourself and meet new friends! Ladies and gentlemen! From December 1 on TV-3 channel a new program TV-CHAT INFON is broadcast Tuesday-Sunday at 01:45am!

I at “JEANSovka”! Call to 0654

Ladies and gentlemen! "Mobile TeleSystems" jointly with MUZ-TV channel offer you a unique opportunity to be on the air!

New Year’s SMS game “Otmorozy Fathers Christmas”

New Year’s SMS game “Otmorozy Fathers Christmas” is the crazy New Year’s fun! Don’t miss your chance to amuse a little!

One more New Year gift: free “golden” number!

MTS is pleased to announce that from December 3, 2003 when signing a contract at own MTS sales offices in Moscow and the Moscow region you can receive an excellent gift — a “golden” federal number.

Merry Fiesta!

Romantic tour for two? Only answer questions! New SMS - contest

Financial Results for the Third Quarter and Nine Months Ended September 30, 2003

Moscow, Russian Federation — December 2, 2003 — Mobile TeleSystems OJSC (“MTS” — NYSE: MBT), the largest mobile phone operator in Russia and Eastern Europe1, today announces its financial and operating results for the third quarter and nine months ended September 30, 20032.

Contact investor relations:

+ 7 495 223 20 25

MTS Investor Relations
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