A method for performing authentication in a communication system comprising an authentication server, and a user profile store storing user profiles for users of the communication system, the method comprising: transmitting from the authentication server to the user profile store a request for the user profile of a user; receiving at the authentication server a response to the request; determining whether the response is indicative of an error; and if the response is indicative of an error, transmitting from the authentication server to the user profile store a message of a type such as to trigger the user profile store to perform a location update procedure in respect of the user.
A method for restricting the use of a mobile terminal including generating a coded value corresponding to a user authentication card, and determining whether or not the mobile terminal is available for use based on the generated coded value. Further, determining whether or not the mobile terminal is available for use includes checking whether or not the generated coded value is on a registration coded value list, and checking whether or not the generated coded value is on a prohibition coded value list if the generated coded value is not on the registration coded value list. The method also includes storing the generated coded value in a temporary coded value list and setting the mobile terminal in a first lock mode when the generated coded value is not on the registration or prohibition coded value lists, transmitting a lost terminal message to a loss management server, determining, by the loss management server, if the mobile terminal has been reported lost, and setting the mobile terminal in a second lock mode if the mobile terminal has been reported lost.
