services offered and the consumers of them. Service Service Operations Operation Example Consumers Nausf_UEAuthentication Authenticate Request/Response Nausf_SORProtection Protect Request/Response Nausf_UPUProtection Protect Request/Response Figure 3.17 - Services offered by the AUSF The AUSF services are described as follows: The Nausf_UEAuthentication service is used to authenticate the UE and is an AKA-based authentication The Nausf_SoRProtection service is provided by the AUSF to steer the roaming information protection service to the requesting NF (UDM) The Nausf_UPUProtection service is provided by the AUSF to protect the UE parameters that update to the requesting NF (UDM) PCF services The PCF provides a list of services to consumer NFs. These services are mostly related to UE policies. The list of services is mentioned in the following list and table, per 3GPP Release 16, 23.502: Building Blocks - Cloud Native Infrastructure The Npcf_AMPolicyControl service is used by the consumer - in this case, the AMF - to create and manage an access and mobility policy for a UE identified by its SUPI. The Npcf_PolicyAuthorization service is provided by the PCF to authorize an Application Function (AF) request and to create policies as requested by an AF for a particular PDU session. The :Npcf_SMPolicyControl service is one of the most critical services offered by the PCF to the SMF. This helps to create and maintain a policy associated with the SMF. The PCF provides information about PDU-session-related policy information. PCC rules are leveraged by the SMF to send traffic policing rules to the UPF, such as throttling a particular subscriber or providing steering rules. Service Name Service Operations Operation Example Consumer(s) Npcf_AMPolicyControl Create Request/Response Update Request/Response UpdateNotify Subscribe/Notify Delete Request/Response Npcf_Policy Authorization Create Request/Response AF and NEF Update Request/Response AF and NEF Delete Request/Response AF and NEF Notify Subscribe/Notify AF, NEF, NWDAF