MSC Server/MSC with Integrated MGCF (MSCF)
Original Publication Date: 2004-Jun-25
Included in the Prior Art Database: 2004-Jun-25
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In the standard architecture of the Internet Multimedia Subsystem (IMS) and the CS (Circuit Switched) domain, as defined in the 3GPP standardization, the Media Gateway Control Function (MGCF) in the IMS and the MSC (Mobile Switching Center) Server in the CS domain perform similar tasks (cf. Figure 1). Both control the MGWs (Media Gateways) and handle the communication between their respective domain and the PSTN/PLMN. Furthermore, the MGCF provides the SIP support, which is often also implemented in the MSC Server as a function called SIP-T (Session Initiation Protocol for Telephony). Because of this analogy, the MGCF functionality can easily be integrated in the MSC Server. Similarly, the MGCF functionality can also be integrated in a MSC so that this MSC serves as a Gateway MSC for both the CS domain and the IMS. A possible implementation of this MSC Server Control Function (MSCF) is shown in Figure 2. The MSCF already includes both the MGW controlling and all ISUP/BICC protocol variants necessary for the interworking with the different PSTN/PLMNs. Also, the interrogation procedure for identifying the called IMS subscriber via the HSS (Home Subscriber Server) is available by using the existing MSC Server respectively MSC features. If the MSC Server already offers a SIP stack, due to a possible SIP-T support, then only an appropriate SIP protocol conversion and the communication with the CSCF/BGCF (Call State Control Function/Breakout Gateway Control Function) has to be added to the MSC Server respectively MSC functionality, which then can be used for other future applications, too. To support PS (Packet Switched) traffic, a Gi interface can be implemented in the MSC. The MSCF and its interfaces is schematically illustrated in Figure 3.