Section: 6.3.10 SMSF discovery and selection
Content: The SMSF selection function is supported by the AMF and is used to allocate an SMSF instance that shall manage the SMS. If the "SMS supported" indication is included in the Registration Request by the UE, the AMF checks SMS subscription from the UDM for the UE on whether the SMS is allowed for the UE. If the SMS is allowed and the UE Context stored in AMF includes an SMSF address, the AMF uses the SMSF address included in UE Context (according to Table 5.2.2.2.2-1 of TS 23.502[ Procedures for the 5G System (5GS) ]  [3]). If the SMS is allowed and the UE Context stored in AMF does not include an SMSF address, the AMF discovers and selects an SMSF to serve the UE. The SMSF selection may be based on the following methods: - SMSF instance(s) address(es) preconfigured in the AMF (i.e. SMSF FQDN or IP addresses); or - SMSF information available in the serving PLMN if received from an old AMF or the UDM; or - The AMF invokes Nnrf_NFDiscovery service operation from NRF to discover SMSF instance as described in clause 5.2.7.3.2 of TS 23.502[ Procedures for the 5G System (5GS) ]  [3]. For roaming scenario, the AMF discovers and selects an SMSF in VPLMN. If the NF consumer performs discovery and selection via NRF, the SMSF selection function in the NF consumer selects a SMSF instance based on the available SMSF instances obtained from the NRF. In the case of delegated discovery and selection in SCP, the NF consumer shall include all available factors in the request towards SCP.