3GPP 23.501 v20.2.0 — the document's own text
Annex L Support of GERAN/UTRAN access
Taught in 10. Radio, Wi-Fi, cable — every way in (The 5G system architecture, in depth).
This annex applies when the SMF+PGW-C is enhanced to support UE accessing the network via GERAN/UTRAN over Gn/Gp interface. For this scenario, the SMF+PGW-C uses N7 interface to interact with PCF and the N40 interface to interact with CHF.
NOTE 1: For the interface with the serving node of the UE, the SMF+PGW-C is assumed to behave as the Control Plane of the PGW described in Annex D of TS 23.401 [26].
SMF+PGW-C selection by SGSN is specified in Annex G of TS 23.502 [3].
The SMF+PGW-C interacting with PCF for GERAN/UTRAN access is specified in Annex G of TS 23.502 [3].
The functional description for SMF+PGW-C interacting with PCF to support GERAN/UTRAN access is specified in TS 23.503 [45].
NOTE 2: Support for IP address preservation upon mobility between 5GS and GERAN/UTRAN for PDN sessions established in EPC is described in clause 5.17.2.4. IP address preservation is not supported for direct mobility between 5GS and GERAN/UTRAN, nor for indirect mobility cases when the PDN session is established in 5GS or in GERAN/UTRAN.
The charging services on SMF+PGW-C interactions with CHF for GERAN/UTRAN access are specified in TS 32.255 [68].