B.7 Provision of Signalling Flow Information at P-CSCF

29.5143GPP5G SystemPolicy Authorization ServiceRelease 18Stage 3TS

When the P-CSCF has successfully concluded the initial registration of an attached UE, i.e., when the P-CSCF has sent to the UE a SIP 200 (OK) response to the SIP REGISTER request, the P-CSCF may provision information about the SIP signalling flows between the UE and itself using the procedure specified in clause 4.2.2.16. If the P-CSCF already has created an "Individual Application Session Context" resource with the PCF related to the signalling with the UE, e.g. one that has been opened according to the procedure described in clause B.4, the P-CSCF shall reuse the already open session to provision the SIP Signalling IP Flow information using the procedure specified in clause 4.2.3.17.

NOTE: This procedure is not applicable for IMS registrations for Emergency sessions.

If the P-CSCF provisions information about SIP signalling flows, the P-CSCF shall ensure that for each signalling IP flow information it provides, the flow descriptions within the "fDescs" attribute shall accurately reflect the IP flow information as seen in the IP header ‘on the wire’. The P-CSCF shall set the value of the "afSigProtocol" attribute to "SIP".

When the P-CSCF de-registers the UE and terminates SIP Signalling to the UE, the P-CSCF shall de-provision the SIP Signalling IP flow information from the PCRF as described in clauses 4.2.2.16 and 4.2.3.17.