Y.4 IP version interworking in IMS

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

A PDU session is associated with either an IPv4 or an IPv6 address. For communication with the IMS, the UE shall acquire an IP address according to TS 23.501 [93], clause 5.8.1.1 for the PDU session. The IP address will be either an IPv4 address or and IPv6 address. Hence, a UE will register to the IMS with either an IPv4 or an IPv6 address. Here the P-CSCF and IMS-AGW may support both IP versions and/or may do interworking depending IP version used within the IMS. If the P-CSCF and IMS-AGW do not support both versions, then network design is expected to ensure that IP address incompatibility does not occur.