Abstract: A location register for a mobile communications network is coupled by an SS7 network for passing messages, has a mated location register at a different location to provide geographical redundancy, and has a status detector for detecting a status of the associated register, by sending a heartbeat message to the associated register. It deduces a fail if the message is returned by the signaling network. A cutover manager is arranged to enable a cutover on the basis of at least the detected status. By providing a more positive detection of a failure than merely passively interpreting a lack of response to the heartbeat, false triggering of cutovers owing to transient failures or temporary congestion, can be reduced. The cutover manager can verify the status by sending other messages by other routes, or using other criteria.

Abstract: An HLR register for maintaining data relating to mobile users of a network for use by the network, the register being arranged to be coupled to a mate register at a remote location for back up of the data, the register being divided into segments and arranged to carry out a partial handover to the mate register by handing over maintenance of data of one or some of the segments to the mate register temporarily. By allowing a partial handover rather than requiring a complete handover, the handover can be simpler and quicker. This can reduce the risk of loss of data or reduce an amount of down time and consequential losses of revenue. This is particularly important for larger registers. The handover can be triggered by a fault in the segment or for the purpose of planned maintenance for example. It can be triggered manually or automatically.

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.