Patent ID: 7003282

Claim:
Authentication method for telecommunication networks, especially for IP networks, in accordance with which method the identity of a subscriber attached to the network is authenticated, characterized by: in a network terminal, using a subscriber identity module essentially of the same kind as in a known mobile communications system, which identity module is such that a response is obtained as a result of a challenge given to it as input, using a special security server in the network so that when a terminal attaches to the network, a message of a new user is transmitted to the security server, fetching subscriber authentication information corresponding to the new user from the mobile communications system to the network, which authentication information contains at least a challenge and a response, wherein after the response to the challenge is generated by the network terminal, the challenge is stored on the network terminal to ensure that the challenge is used once, and performing authentication based on the authentication information obtained from the mobile communications system by transmitting the challenge to the terminal through the network, by checking that the challenge is unique from challenges used in previous authentication exchanges, by generating, if the challenge is unique and is not stored on the network terminal, the response from the challenge in the identity module of the terminal and by comparing the response with the response received from the mobile communications system.