This TS defines interworking procedures between a 3GPP CS domain (see TS 23.205
applies either BICC or ISUP as signalling protocol, and external networks that use SIP-I (see ITU-T Q.1912.5,
Profile C) as signalling protocol.
The document also describes the related interworking architecture. The control plane interworking is performed by an interworking unit at the interconnection between the 3GPP CS domain and an external SIP-I network. The user plane interworking is performed by an MGW. This TS defines stage 2
procedures for the control of the MGW.
The present specification reuses existing interworking procedures of TS 29.163
and ITU-T Q.1912.5,
Profile C, as far as possible.