A.6 Notification IP-CAN Type Change

29.2143GPPPolicy and charging control over Rx reference pointRelease 17TS

When the P-CSCF receives an initial REGISTER SIP message or an INVITE SIP message from an attached UE, the P-CSCF may request from the PCRF the information about the type of IP-CAN the UE is attached to using the procedure specified in clause 4.4.1.

NOTE 1: This procedure is not applicable for IMS registrations for Emergency sessions.

NOTE 2: The P-CSCF can request information about the type of IP-CAN as part of the SIP session setup when it is only interested in the related information when the IMS session is ongoing.

If the P-CSCF requests information about the type of IP-CAN, the P-CSCF shall also subscribe within the same AAR command operation to notifications for changes of the IP-CAN type used by the UE. The P-CSCF shall include a Specific-Action AVP in the AAR that is set to the value of IP-CAN_CHANGE.

When the P-CSCF receives the AA-Answer or RA-Request from the PCRF, the P-CSCF stores the IP-CAN type information received within the IP-CAN-Type AVP and the RAT type information received within the RAT-Type AVP and AN-Trusted AVP (if also provided by the PCRF) and behaves as defined in 3GPP TS 24.229 [17].

The P-CSCF may receive notifications for changes of the IP-CAN type from the PCRF according to clause 4.4.6.4. When the P-CSCF receives a notification of the change of the IP-CAN used by the UE, the P-CSCF stores the new IP-CAN type information and RAT type information and behaves as defined in 3GPP TS 24.229 [17].

NOTE 3: The subscription to receive information about the type of IP-CAN will be cancelled when the corresponding Rx session is terminated by the AF (i.e. when the UE is de-REGISTERED or the related SIP call is torn down).