Mobile Application Part (MAP) messages sent between mobile switches and databases to support user authentication, equipment identification, and roaming are carried by TCAP. In mobile networks (IS-41 and GSM) when a mobile subscriber roams into a new mobile switching center (MSC) area, the integrated visitor location register requests service profile information from the subscriber's home location register (HLR) using MAP (mobile application part) information carried within TCAP messages.
The Mobile Application Part (MAP), one of protocols in the SS7 suite, allows for the implementation of mobile network (GSM) signaling infrastructure. 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. Conversely, the HLR is updated as the subscriber moves about the network and is thus serviced by different switches within the network.
MAP has been evolving as wireless networks grow, from supporting strictly voice, to supporting packet data services as well. The fact that MAP is used to connect NexGen elements such as the Gateway GPRS Support node (GGSN) and Serving Gateway Support Node (SGSN) is a testament to the sound design of the GSM signaling system.
MAP has several basic functions:
* Mechanism for a Gateway-MSC (GMSC) to obtain a routing number for an incoming call
* Mechanism for an MSC via integrated Visitor Location Register (VLR) to update subscriber status and routing number.
* Subscriber CAMEL trigger data to switching elements via the VLR
* Subscriber supplementary service profile and data to switching elements via the VLR.