Disaster recovery for very large GSM/UMTS HLR databases

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.