A method of registering a mobile device in a mobile telecommunications network comprises the device's receiving power from a power source and transmitting a registration request signal including mobile device identification data, an associated mobile network determining a set of latitude and longitude location coordinates for the transmitting mobile device, comparing the determined set of latitude and longitude location coordinates with a table for matching the location coordinates with a service area code, determining a service area code responsive to the comparison, and storing the service area code, the mobile device identification data, the determined service area code and a location area code of the associated public mobile network for registering the mobile device in the associated mobile network. A related mobile device comprises a power source, a processor for determining whether power has been actuated, a global positioning system for determining a set of latitude and longitude location coordinates for the transmitting mobile device, the processor for comparing the determined set of latitude and longitude location coordinates with a table for matching the location coordinates with a service area code, determining a service area code responsive to the comparison and storing the service area code in memory of the mobile device.