Mobile application part is an SS7 protocol used for setup and control of wireless calls via the public switched telephone network, providing an application layer for the nodes in GSM, UMTS, and GPRS networks.
The premise behind MAP is to connect the distributed switching elements, called mobile switching centers (MSCs) with a master database called the Home Location Register (HLR). The HLR dynamically stores the current location and profile of a mobile network subscriber. The HLR is consulted during the processing of an incoming call and updated as the subscriber moves through the network and serviced by different switches within the network.