The basic functions of the MSC (Mobile-services Switching Center), which provides a service in CS (Circuit Service) mode, are circuit switching, signaling processing and mobility management (MM). Interconnection between the entities of the Network Sub-System is achieved by a SDH (Synchronous Digital Hierarchy) transmission network.
The NGN (Next Generation Network) is an evolution of the NNS core network. Signaling processing and MM are provided by a stand-alone entity, the MSC Server. The interconnection between the entities of the NGN is operated by the same Internet Protocol (IP) network deployed for the GSS (GPRS Sub-System).
Section 4.1 explains the architecture of the NGN and describes the components, the MSC Server and the MGW (Multimedia GateWay) and SGW (Signaling GateWay) providing the interfaces with the PLMN (Public Land Mobile Network) or PSTN (Public Switched Telephone Network) third-party networks, BSS (Base Station Sub-system) or UTRANs (UMTS Terrestrial Radio Access Networks).
Section 4.1 also introduces the protocol architecture implemented for signaling and media transport on an IP network, for the control of the gateways by the MSC server and for dialog between the MSC Servers.
Section 4.2 describes the procedures concerning the establishment of a communication during an incoming or outgoing call, release of the communication and management of the mobile on the move (handover).
The MSC and ...