ls NAS message security PDU session control Measurement reports management Management of radio resources (admission and control) Flow routing Scheduling of resources allocated to mobiles Anchor point Figure 1.7. The functional separation between NG-RAN and 5GC 1.3.1. Mobile identities 1.3.1.1. The identity of the mobile at the level of the AMF Registration procedure occurs when the mobile switches on. If authentication succeeds, the state of the mobile changes from the RM-DEREGISTERED state to NG-RAN and 5G-NR the RM-REGISTERED state and a user context (UE Context) is created on the During the registration procedure, the AMF registers the IMSI (International Mobile Subscriber Identity) from its private identifier SUPI or private and hidden identifier SUCI. The SUPI and SUCI identifiers allow the core network to identify the subscription associated with the mobile. The identifier format matches with the description of the NAI (Network Access Identifier) in order to be compatible with the DNS (Domain Name Server) servers by respecting the RFC7542 specification. The SUPI identifier consists of two fields: the type of SUPI identifier (IMSI Identifier (International Mobile Subscriber Identity) or an identifier specific to the operator network) and the IMSI identity value or specific NAI value. The SUCI identifier is made up of six fields defined as follows (Figure 1.8): type <supi type> hni <home network identifier> rid <routing indicator>.schid <protection scheme id .hnkey <home network public key id>.out <HPLMN defined scheme out>. Protection HN PKI Output Figure 1.8. The fields of the SUCI identifier The SUPI type value is used to indicate whether the SUPI identifier corresponds to the IMSI identity (type = 0) or a network-specific identifier (type = 1). The hni field corresponds to the country code (MCC (Mobile Network Country)) and the operator code (MNC (Mobile Network Code)). The ri field is defined over four digits. The default value is 0, but a specific value is used to identify on which partition of the UDR 