STRATEGIC COOPERATION AGREEMENT

Exhibit 4.31

STRATEGIC COOPERATION AGREEMENT

Between

T-Mobile International AG & Co. KG

Landgrabenweg 151

53227 Bonn

Germany

(“ TMO ”)

and

MATAV Rt.

Hungary

Address: 1013 Budapest, Krisztina krt. 55

(“ MATAV ”)

together referred to as “Parties”

1

Preamble

1.              MATAV and TMO belong to the Deutsche Telekom (“DT”) group.             T-Mobile Hungary Rt. , (“TMH”) is a wholly owned subsidiary of MATAV. TMO is responsible within DT to manage the mobile business of the DT group.

2.              In order to also make use of TMO’s expertise in Hungary, MATAV wants TMO’s support to manage the mobile business and leverage synergies for TMH, MATAV and TMO.

3.              In order to realize this effectively TMO needs to conclude a strategic cooperation contract with MATAV.

Therefore , the Parties now agree,

§ 1 Management of TMH

1.              TMH was established by closed foundation on October 27, 1993, pursuant to Act VI of 1988 on Business Organizations, as amended, Act XVI of 1991 on Concessions, Act LXXII of 1992 on Telecommunication and the original Deed of Association. According to the Deed of Association, the business of TMH is managed by or under the direction of its Board of Directors according to the Rules of Operations of the Board of Directors.

Based on the Concession Agreement between the Minister of Transport, Communication and Water Management, the purpose of the Concession Company is to provide public GSM 900 and DCS 1800 integrated public mobile radio telephone services. In addition, the purpose of the Concession Company is to be engaged  in such other activities which are necessary for the realisation of the concession activity mentioned above, and for activities permitted by the Concession Contract on the basis of the Telecommunications Law .

2.              MATAV and TMO will coordinate their efforts to guarantee proper and orderly cooperation in the management of TMH as direct shareholder and shareholder support respectively.

3.              Cooperation projects directly relating to TMO’s expertise in the mobile communications business or other areas (e.g. t-zones) may be delegated by TMH´s Board to TMO for TMO´s sole responsibility.

4.              The Parties agree that main target is to maximise TMH’s shareholder value which is best achieved by maintaining the position in the market as the market leading

6/2

operator in Hungary, and when they exercise their rights and duties under this Agreement, they shall consider such main target as the priority.

5.              According to the guidelines in Section 4. of §1. above, in the event there is an immediate requirement for action in the mobile and/or related markets in Hungary, in particularly in the fulfillment of the main targets of the relevant business plan/budget of TMH, both TMO and MATÁV authorize TMH to act with immediate effect, provided that the action falls within the business plan, and provided further that if the by-laws of TMH or prevailing laws refer an issue to the exclusive competence of the Board of Directors or the Shareholders Meeting of TMH, such exclusive competence shall remain unaffected and the management of TMH may only act subject to the approval of the Board of Directors or the Shareholders Meeting. In such event TMH shall inform both TMO and MATÁV in writing about the actions made.

§ 2 Shareholder Right

1.              As a general rule, MATAV and TMO shall harmonise their position and will provide their joint and unanimous advice to TMH’s Supervisory Board and Board of Directors and Top Management of TMH.

2.              The cooperation concerning the management of TMH between MATAV and TMO shall not aff