Y.8 Support for Paging policy differentiation for IMS services

23.2283GPPIP Multimedia Subsystem (IMS)Release 18Stage 2TS

P-CSCF may support Paging Policy Differentiation (as defined in TS 23.501 [93]) for a specific IMS service by marking packet(s) to be send towards the UE related to that IMS service. For such an IMS service, a specific DSCP (IPv4) value and/or a specific Traffic Class (IPv6) value are assigned by local configuration in the P-CSCF.

NOTE 1: The packet marking used for Paging Policy Differentiation can also be used for determination of the Paging Cause, for the Multi-USIM UE support, by the relevant 5GS node.

When Paging Policy Differentiation is deployed in a PLMN, all P-CSCF entities of that PLMN shall homogeneously support it and shall be configured with the same policy for setting the specific DSCP (IPv4) and/or Traffic Class (IPv6) values used by P-CSCF for that feature.

NOTE 2: It is assumed that the DSCP / Traffic Class header is not rewritten by intermediate routers between the P-CSCF and the UPF.