A caller identifier is assigned to a group profile.

The base station transmits a reference signal generated on the basis of a terminal identifier in the subframe.

During the session negotiation, each AN establishes a new session and allocates a new Unicast Access Terminal Identifier (UATI).

The method includes receiving the FTCMAC.UATIReceived indication and determining if an Access terminal Identifier (ATIdentifier) that accompanies the FTCMAC.UATIReceived indication matches the ATIdentifier last transmitted by the access terminal.

The correlation may be direct, as by unique terminal identifier, or by a comparison of databases stored by computers.

Through the present invention, optional information such as a terminal identifier can be carried by modifying the content of the persistent resource allocation message.

In one embodiment, the access terminal identifier is a long code mask based on a subnet identifier.

When a call to that extension is detected, the communications switching system reports this to the host computer which stores a set of at least one characteristics of the calling telephone terminal including a unique terminal identifier.

At least one first ciphering key according to the mobile network is calculated in the mobile network and in the terminal for a terminal identifier using a specific secret key for the identifier.