A.4 Notification of AF Signalling Transmission Path Status

29.2143GPPPolicy and charging control over Rx reference pointRelease 17TS

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 4.4.5. Once the P-CSCF has subscribed, the P-CSCF may receive notifications from the PCRF according to clause 4.4.6.3.

NOTE 1: When the Standardised QCI characteristics as defined in 3GPP TS 23.203 [2] are followed, the QCI for IMS signalling will correspond to a non-GBR bearer. In this case, the P-CSCF will not receive notifications related to the Specific-Action with value "INDICATION_OF_LOSS_OF_BEARER".

NOTE 2: 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 PCRF, the P-CSCF shall behave as defined in 3GPP TS 24.229 [17].