B.4 Notification of AF Signalling Transmission Path Status

29.5143GPP5G SystemPolicy Authorization ServiceRelease 18Stage 3TS

When the P-CSCF receives an initial REGISTER SIP message from an attached UE, the P-CSCF may subscribe to notifications of the status of the AF signalling transmission path using the procedures specified in clause 4.2.6.7. Once the P-CSCF has subscribed, the P-CSCF may receive notifications from the PCF according to clause 4.2.5.10.

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

The P-CSCF shall cancel the subscription to notification of the status of the AF signalling transmission path when the AF signalling to that particular user is terminated (i.e. when the user is de-REGISTERED from the IM CN subsystem).

When the P-CSCF receives a notification of loss of signalling connectivity from the PCF, the P-CSCF shall behave as defined in 3GPP TS 24.229 [32].