The Mobile Application Part (MAP), one of the protocols in the SS7 suite, allows for the implementation of the 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
- A 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
· Length – The length of the packet.
· MAP parameters – Various parameters depending on the operation.
· Operation specifier – The type of packet. The following operations are defined:
MAP is defined by ITU-T as part of SS7 protocols.
SS7 Fundamentals are available at Q.700