7.2.1 Services performed by network entities in the control plane
29.1633GPPInterworking between the IP Multimedia (IM) Core Network (CN) subsystem and Circuit Switched (CS) networksTS
7.2.1.1 Services performed by the SS7 signalling function
The SS7 signalling function provides the capabilities to deliver or receive SS7 MTP3-User information (e.g. ISUP or BICC+STCmtp) across the SS7 signalling network. The functional interface of the MTP, the MTP User parts and the signalling network are as detailed in ITU-T Recommendations Q.701 to Q.709 [3].
7.2.1.2 Services of the SGW
The SGW shall perform the functions as described in 3GPP TS 23.002 [10].
In order to support the seamless operation of the MTP3-User part information between networks incorporating SS7 and IP (either Ipv4, see RFC 791 [16], or Ipv6, see RFC 2460 [39]), the SGW shall support the services of MTP as well as the services of the M3UA (see 3GPP TS 29.202 [20]) and SCTP (see RFC 2960 [18]).
7.2.1.3 Services of the MGCF
The session handling and session control of the MGCF shall be as detailed in 3GPP TS 24.229 [9].
The MGCF shall provide the interaction, through the use of its interworking function, between the SS7 MTP3-User part information, e.g. ISUP, and SIP. The MGCF interworking function shall also provide the translation between the SS7 MTP3-User part information and SIP, where the interworking of SIP to ISUP and BICC+STCmtp are detailed below.
7.2.1.4 Services of the SIP signalling function
The SIP signalling function is a logical entity that provides the capabilities to deliver or receive multimedia session information across the IM CN subsystem signalling system.