Abstract: A method of and apparatus for defining a zone, comprising receiving (S3) location data indicative of the location of a device 2 at a plurality of times, determining (S14), based on the location data, information relating to the occupancy of the device in a plurality of geographical regions, and defining (S15), based on the information, at least one zone. The or each zone consists of multiple contiguous regions of the geographical regions in which the occupancy of the device meets at least one criterion. Each of the plurality of predetermined geographical regions is defined independently of location areas over which base stations transmit and receive.

Abstract: A method comprising maintaining (A, B), by a device (6), communication with a monitoring unit (7); determining, by the device, an absence of communication from the monitoring unit; based at least on a result of said determining, starting monitoring (F) of at least one variable related to distance moved by the device and/or time elapsed; if the at least one variable meets at least one criterion, determining that the absence of communication from the monitoring unit is not due to a blind spot. A device securely attachable to a person (5) may be configured to carry out this method, which may be user in offender monitoring.

Abstract: A method of and apparatus for defining a zone, comprising receiving (S3) location data indicative of the location of a device 2 at a plurality of times, determining (S14), based on the location data, information relating to the occupancy of the device in a plurality of geographical regions, and defining (S15), based on the information, at least one zone. The or each zone consists of multiple contiguous regions of the geographical regions in which the occupancy of the device meets at least one criterion. Each of the plurality of predetermined geographical regions is defined independently of location areas over which base stations transmit and receive.