A mobile switching center ( MSC) is the central switching system in digital cellular networks that performs the long-distance switching functions. As a component of the switching subsystem( SSS), the MSC center connects to the mobile stations ( MS) located within the MSC area through the radio base control( BSC) and through the base station( BS).
The MSC Area means the geographical area served by the MSC. This can consist of one or more Location Areas( LA). In addition, the MSC center creates the connection to subscribers in fixed networks such as the Public Switched Telephone Network( PSTN) or the ISDN network, to public data networks and some private networks.
MSCs consist of ISDN exchanges and handle their communications with exchanges in PSTNs over PCM links, using SS7 signaling. In order to support circuit-switched voice transmission and packet-oriented data transmission in General Packet Radio Service( GPRS), the signaling connections are both circuit- and packet-oriented. The signaling procedures can be performed separately or in combination.
The mobile switching centers have several databases in which the location directory( HLR), the visitor directory( VLR), the equipment database( EIR) and the authentication characteristics( AC) are stored.