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5GS – General Registration – 23 of 24
Signalling flow for TS 23.502 General Register - AMF to UE: Registration Accept

Step 21, verbatim
New AMF to UE: Registration Accept (5G-GUTI, Registration Area, Mobility restrictions, PDU Session status, Allowed NSSAI, [Mapping Of Allowed NSSAI], Periodic Registration Update timer, LADN Information and accepted MICO mode, IMS Voice over PS session supported Indication, Emergency Service Support indicator).
The AMF sends a Registration Accept message to the UE indicating that the Registration Request has been accepted. 5G‑GUTI is included if the AMF allocates a new 5G‑GUTI. If the AMF allocates a new Registration area, it shall send the Registration area to the UE via Registration Accept message. If there is no Registration area included in the Registration Accept message, the UE shall consider the old Registration Area as valid. Mobility Restrictions is included in case mobility restrictions applies for the UE and Registration Type is not Emergency Registration. The AMF indicates the established PDU Sessions to the UE in the PDU Session status. The UE removes locally any internal resources related to PDU Sessions that are not marked as established in the received PDU Session status. When the UE is connected to the two AMFs belonging to different PLMN via 3GPP access and non-3GPP access then the UE removes locally any internal resources related to the PDU Session of the current PLMN that are not marked as established in received PDU Session status. If the PDU Session status information was in the Registration Request, the AMF shall indicate the PDU Session status to the UE. The Mapping Of Allowed NSSAI is the mapping of each S‑NSSAI of the Allowed NSSAI to the S‑NSSAIs of the Configured NSSAI for the HPLMN. The AMF shall include in the Registration Accept message the LADN Information for LADNs, defined in TS 23.501 [2] clause 5.6.5, that are available within the Registration area determined by the AMF for the UE. If the UE included MICO mode in the request, then AMF responds whether MICO mode should be used. The AMF sets the IMS Voice over PS session supported Indication as described in clause of TS 23.501 [2]. In order to set the IMS Voice over PS session supported Indication the AMF may need to perform the UE/RAN Radio information and Compatibility Request procedure in clause 4.2.8 to check the compatibility of the UE and RAN radio capabilities related to IMS Voice over PS. If the AMF hasn't received Voice Support Match Indicator from the NG-RAN on time then, based on implementation, AMF may set IMS Voice over PS session supported Indication and update it at a later stage. The Emergency Service Support indicator informs the UE that emergency services are supported, i.e. the UE is allowed to request PDU Session for emergency services.
The Handover Restriction List and UE-AMBR are provided to NG-RAN by AMF in this step.
For an Emergency Registered UE, there is no AS security context information included in the N2 control messages and there is no NAS level security when the UE cannot be authenticated.