Abstract: There is therefore provided a method of estimating the location of a mobile device, the mobile device being configured for use in a cellular mobile communications network comprising a plurality of base stations, the method comprising generating a database of locations visited by the mobile device by obtaining measurements of the position of the mobile device over time using a satellite-based positioning system; obtaining the identity of the base station serving the mobile device at the time of each measurement of the position of the mobile device; and analyzing the measurements to identify locations visited by the mobile device, each location being associated with a particular base station, such that the mobile device is attached to said base station when at said location; and during subsequent use of the mobile device, in the event that it is not possible to use the satellite-based positioning system to measure the position of the mobile device, estimating the location of the mobile device as one or more ide