Controlling access to terminals in a telecommunications system

When a subscriber to mobile telecommunications network A roams in mobile telecommunications network B using their mobile terminal MS 30B, calls to them, for example from calling mobile terminal MS 30A, are routed via HLR 40A of network A. HLR 40A is connected to a time zone data processing module 50 which stores data relating to the time zone within which network B is located. This allows time zone data processing module 50 to calculate whether the call from MS 30A is likely to be received at an inconvenient time (for example in the early hours of the morning) by roaming subscriber of MS 30B in network B. If it is determined that the call is likely to be received at an inconvenient time by the subscriber MS 30B, the caller is advised of this and is given the option to store a voice or SMS message which will be transmitted by the time zone data processing module 50 to the subscriber of MS 30B at a more convenient time. The times at which the subscriber MS 30B receives communications are selectable by the subscriber.