Abstract: In a cellular communications system comprising a plurality of zones, details of authorized services for each mobile terminal are stored at a central register. The central register is accessed on entry of a visiting mobile terminal into that zone whereby to retrieve the service details for that mobile, the retrieved details are stored at a local register and compared with a set of services capable of being supported within the zone, and providing to the terminal information relating only to those services that are both authorized for use by the terminal and capable of support within the zone. In a preferred embodiment, information relating to a service which cannot be supported in a particular zone is not forwarded to the local register thus avoiding message rejection by the local register.