Patent ID: 7248886

Claim:
A method of operating a cordless communication system comprising a mobile terminal of a public cellular communication system and having a base station which is connectable to a public fixed network and compatible at an air interface with the cellular communication system that has at least one authentication function, comprising: reading and writing from and to, respectively, at least a first subscriber identity module through a read and write unit of the base station, wherein sections of data of the first subscriber identity module used in the base station are identical to sections of data stored on a second subscriber identity module of a mobile terminal authorized to access the public cellular communication system; processing data read from the first subscriber identity module through software implemented in the base station, using a random number generated at the base station, so as to generate a first authentication result; processing data read from the second subscriber identity module, using the random number generated at the base station, so as to generate a second authentication result; authenticating the mobile terminal with regard to the base station through the first authentication result and the second authentication result, wherein the base station fulfills the same functions and tasks with respect to access control and authentication as a home location register and, respectively, an authentication center of the public cellular communication system, and wherein the authentication is performed without accessing a home location register in the public cellular communication system; and operating the mobile terminal through the public fixed network if the authentication has been successful.