4.1 General

23.2313GPPRelease 17SIP-I based circuit-switched core networkStage 2TS

The SIP-I circuit switched core network supports the IP transport mechanism. The passage of compressed speech at variable bit rates is possible through the CS core network.

The CS core network shall employ the MSC server, GMSC server and media gateways. The GMSC server and MSC server shall provide the call control and mobility management functions, and the media gateway shall provide the bearer control and transmission resource functions. The media gateway shall contain the stream manipulating functions.

The GMSC server and MSC servers are connected to the media gateway via the Mc reference point. The MSC servers and GMSC servers are connected with the Nc reference point. There may be a number of call control transit nodes between the MSC server and GMSC server in the Nc reference point. The MGWs are connected with the Nb reference point.

The users connected to the CS core network shall not be aware whether a MSC server – media gateway combination is used or a monolithic MSC is used.