5.10 P-CSCF Restoration in EPC for untrusted WLAN when N10 is used instead of S6b

23.3803GPPIMS Restoration ProceduresRelease 17TS

If the IMS service is required to be served by untrusted WLAN where N10 is used instead of S6b interface as specified in 3GPP TS 23.502 [29], the AAA registers itself in HSS+UDM via SWx interface, and PGW-C+SMF registers itself in HSS+UDM via N10.

When P-CSCF restoration indication is received, the HSS+UDM shall send a P-CSCF restoration indication via N10 interface to the PGW-C+SMF serving the IMS PDN connection as described in clause 5.9 to continue with the P-CSCF restoration.