Mobile Application Part

Chapter 12 has described the signaling between a mobile station (MS) and a mobile switching center (MSC) in a cellular (public land) mobile network (CMN, PLMN). The present chapter describes the mobile application part (MAP) of signaling system No.7 (SS7). MAP defines a number of remote operations (transactions) that support mobile telecommunications.

Public switched telecommunication networks (PSTN) are fixed networks. A subscriber line is fixed (attached) to a local exchange, which has a record for each of its subscribers. The record contains semipermanent and temporary data. Semipermanent data in the record include the subscriber's directory number and a service profile. This is a list of features (for example, call waiting) which the subscriber has requested, and the telecom has agreed to supply, for a monthly or per-use charge.

The temporary data include information on the current subscriber state (busy, idle, denied service), and, during the times that the subscriber is involved in a call, details about the connection. The exchange consults these data when processing the subscriber's calls.

When a MSC is serving a MS, it needs similar data. However, a MS is "mobile." At different points in time, it can be in the service area of different MSCs. It is not practical to store the information on all mobiles at every MSC. Instead, this information is stored in centralized databases. One of the purposes of MAP transactions is to enable the MSCs to obtain information about a MS from these databases.

This chapter describes two versions of MAP. The U.S. version, denoted here as IS-MAP, is defined by the Electronic Industries Association (EIA) and the Telecommunications Industry Association (TIA). The international version, used in the Global System for Mobile Communications (GSM), and denoted here as GSM-MAP, is standardized by the International Telegraph and Telephone Consultative Committee (CCITT)/International Telecommunications Union (ITU-T) and the European Telecommunications Standards Institute (ETSI).

IS-MAP is discussed in Sections 17.1-17.5. The description of GSM-MAP starts in Section 17.6.

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