June 2003

The most wanted tariff of the year — Super JEANS!

June 30, 2003 — The group of JEANS tariffs is added now by a new tariff plan Super JEANS. A new unique offer within the JEANS group is developed taking into account wants and needs of the largest segments of potential and current cellular users. Unlimited validity periods of payments and the unified call fee are the main benefits of Super JEANS.

New unified tariff for intranet roaming

MTS launches the unified tariffs for intranet roaming in Russia. From now on when the MTS user is in any Russia’s region covered by the MTS network, mobile calls will be charged under the same tariff. For example, the per minute cost of the call originated to MTS phones is 19 cents only.

Reduced roaming in Ukraine

MTS is pleased to announce the launch of reduced roaming for MTS users of the UMC network in Ukraine.

Mobile TeleSystems (MTS) Financial Results for the First Quarter Ended 31st March 2003

Moscow, Russian Federation — June 26, 2003 — Mobile TeleSystems OJSC (“MTS” — NYSE: MBT), the largest mobile phone operator in Russia and Central and Eastern Europe1, today announced its financial results for the first quarter ended March 31, 2003.

MTS CUP on sport sheat-fish fishing

MTS presents: First Russia’s Open Cup on sport sheat-fish fishing in the Lower Volga!

MTS Increases Ownership in UMC to 83.7%

Moscow — June 16, 2003 — Mobile TeleSystems OJSC (“MTS” — NYSE: MBT), the largest mobile phone operator in Russia and Central and Eastern Europe1 today announces that it has increased its ownership in Ukrainian Mobile Communications (UMC) to 83.7% through the acquisition of an additional 26% stake in the company.

Intranet roaming in Rostov-na-Donu

MTS is pleased to announce that from June 10, 2003 you do not need to activate “International and national roaming” to use the mobile phone in Rostov-na-Donu and the Rostov region (the “Dontelecom” operator, the network code is 250 10, displayed as RUS-10, RUS DTC, 250 10). Your phone will be automatically registered in the region’s coverage zone and you will be able to enjoy all benefits of intranet roaming!

Contact investor relations:

+ 7 495 223 20 25 ir@mts.ru

MTS Investor Relations
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