Section: Annex L (normative): Support of GERAN/UTRAN access
Content: 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[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [26]. SMF+PGW-C selection by SGSN is specified in Annex G of TS 23.502[ Procedures for the 5G System (5GS) ]  [3]. The SMF+PGW-C interacting with PCF for GERAN/UTRAN access is specified in Annex G of TS 23.502[ Procedures for the 5G System (5GS) ]  [3]. The functional description for SMF+PGW-C interacting with PCF to support GERAN/UTRAN access is specified in TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [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[ Telecommunication management; Charging management; 5G data connectivity domain charging; Stage 2 ]  [68].