The A-GPS uses the space segment of the GPS, cellular networks and mobile phones or smartphones which do not necessarily have their own real GPS module for position finding. The A-GPS is a paid service. In the online mode, which is the basic one, the coordinates are determined outside the terminal device, thus it is not necessary to have a real GPS module. However, thick cellular network coverage is needed. In the offline mode the A-GPS system is used to transmit an almanac and ephemerides through the cellular network, which decreases the time of the cold and warm start for a real GPS-receiver.