Subscriber server system for a cellular communication system

A subscriber server system for a cellular communication system, the subscriber server system comprising:

• means for storing public identities associated with subscribers of the cellular communication system;
• means for receiving an identity information request message from a remote station, the identity information request message comprising a first public identity for a subscriber of the cellular communication system;
• determining means for determining a first set of public identities in response to the public identity, the first set comprising a plurality of public identities associated with the subscriber;
• generating means for generating an identity response message comprising an indication of the first set of public identities;
• and
• means for transmitting the identity response message to the remote station;
• wherein the generating means is arranged to add a number of private headers for indicating public identities of at least some of the first set of public identities;
• and
• wherein the generating means is arranged to add a private header comprising an indication of the public identity and associated device capabilities for at least the public identities of the first set not being the first identity.