7.1 Reference Model

29.2353GPPInterworking between SIP-I based circuit-switched core network and other networksRelease 17TS

7.1.1 General

Figure 7.1.1.1 details the reference model required to support interworking between the 3GPP IM CN subsystem, as specified in 3GPP TS 23.228 [11] and 3GPP TS 24.229 [12] and a SIP-I based circuit-switched core network, as specified in 3GPP TS 23.231 [3] and 3GPP TS 29.231 [4].

NOTE 1: The IM-MGW may be connected via the Mb to various network entities, such as a UE (via a GTP Tunnel to a GGSN), an MRFP, a TrGW or an AGW.

Figure 7.1.1.1: IM CN subsystem to CS network logical interworking reference model

Nb reference point: The Nb reference point is defined in accordance with 3GPP TS 29.414 [43].

Nc reference point: The Nc reference point is defined in accordance with 3GPP TS 29.231 [4].

Mg reference point: The Mg reference point is defined in accordance with 3GPP TS 24.229 [12].

Mj reference point: The Mj reference point is defined in accordance with 3GPP TS 24.229 [12].

Mb reference point: The Mb reference point is defined in accordance with 3GPP TS 23.002 [2].

Mn reference point: The Mn reference point is defined in accordance with 3GPP TS 29.332 [54].

7.1.2 Signalling interactions between network entities in the control plane

The control plane between the IM CN Subsystem supporting SIP and a 3GPP CS network supporting a SIP-I based Nc interface is as shown in figure 7.1.2.

Figure 7.1.2.1: Control plane interworking protocol stack between the IM CN subsystem and a 3GPP CS network supporting SIP-I based Nc interface

Signalling between the SIP signalling function and the MGCF uses the services of IP (RFC 2460 [17]), and transport protocol such as TCP (RFC 793 [16]) or UDP (RFC 768 [15]) or SCTP (RFC 4960 [18]) (see TS 24.229 [12]), and SIP.

Signalling between the SIP-I signalling function and the MGCF uses the services of IP (IETF RFC 791 [14] or IETF RFC 2460 [17]), SCTP (IETF RFC 4960 [18]) and SIP-I.