This TR gives examples of the session setup in the IM CN subsystem based on SIP and SDP. These signalling flows provide detailed signalling flows, which expand on the overview information flows provided in TS 23.228
. The flows focus on a basic session setup, i.e. no flows will be provided for topology hiding, for sessions with IBCF involved or for sessions having certain features.
The signalling flows provided in this TR follow the methodology developed in TS 24.228
. The following additional considerations apply:
TS 24.228 shows separate signalling flows with no configuration hiding between networks, and with configuration hiding between networks. Separate signalling flows are not shown in this TR;
TS 24.228 breaks down the functionality of the various CSCFs. The functionality of the S-CSCF and I-CSCF is not relevant for the session setup procedure. Therefore S-CSCFs and I-CSCFs are collapsed into a single entity labelled "Intermediate IM CN subsystem entities".