Patent ID: 7433453

Claim:
A method of transmitting service data between a first telecommunication device and a second telecommunication device of a telecommunication network, a central module generating prepaid access data, the prepaid access data comprising a first digital key and control data, and the prepaid access data being stored in a memory module of the first telecommunication device, and the central module generating a second digital key, assigned to the first digital key, the second digital key being stored on one or more control units of the telecommunication network, wherein the first telecommunication device determines a validity criterion based on control data of the prepaid access data, and encodes service data of the first telecommunication device by the first key, as long as the validity criterion is fulfilled, and the first telecommunication device transmits encoded service data to the control unit, the control unit checking by the second digital key that the encoded service data are encoded with the first digital key, upon a successful check the control unit decoding the encoded service data, and the control unit transmitting the decoded service data to the second telecommunication device.