W.2 Architecture
23.2283GPPIP Multimedia Subsystem (IMS)Release 18Stage 2TS
W.2.1 EPS
The architecture to support IMS services for roaming users, including Voice over IMS, in deployments without IMS-level roaming interfaces is shown in figure W.2-1
The following architecture requirements apply:
– P-CSCF (at HPLMN) identifies the serving network (VPLMN) where the UE is located using the procedure defined in clause W.3.
Figure W.2-1: architecture IMS architecture
W.2.2 5GS
See clause Y.9.2.