B.13 Notification of PLMN Change

29.5143GPP5G SystemPolicy Authorization ServiceRelease 18Stage 3TS

When the P-CSCF receives an initial SIP REGISTER message from an attached UE, the P-CSCF may subscribe to notifications of PLMN changes corresponding to the identity of the network (either a PLMN or an SNPN) where the UE is located using the procedure specified in clauses 4.2.2.2, 4.2.3.2 and 4.2.6.2.

NOTE: For a UE located in an SNPN the SNPN Identifier consisting of the PLMN Identifier and the NID is provided.

When the P-CSCF receives the subscription request response in an HTTP response or the notification of PLMN change in an HTTP POST request from the PCF, the P-CSCF shall store the PLMN Identifier and, if available, the NID received within the "plmnId" attribute and use the received information as per P-CSCF procedures in 3GPP TS 24.229 [32].

The P-CSCF shall cancel the subscription to notification for changes of the PLMN used by the UE when the user is de-registered from the IM CN subsystem.