UE-Initiated Deregistration Call Flow

This section describes the UE-Initiated Deregistration call flow.

The deregistration procedure allows the UE to inform the network that it does not want to access the 5G data services.

UE-Initiated Deregistration Call Flow
UE-Initiated Deregistration Call Flow Description

Step

Description

1, 2

The UE sends the NAS message Deregistration Request (5G-GUTI, Deregistration type, Access Type) to the AMF.

3

If the PDU session has been established, the AMF sends Nsmf_PDUSession_ReleaseSMContext (SUPI and PDU Session ID) to SMF. All the PDU sessions over the target access, which belong to the UE are released by the AMF by sending Nsmf_PDUSession_ReleaseSMContext Request (SUPI, PDU Session ID) message to the SMF for each PDU session.

4

The SMF releases all resources (for example, the IP address or prefixes that were allocated to the PDU session) and the corresponding User Plane resources. The SMF responds with Nsmf_PDUSession_ReleaseSMContext Response message.

5

The AMF invokes the Nudm_UECM_Deregistration service operation so that the UDM removes the association it had stored.

6

If there is any association with the PCF for this UE and the UE is no more registered over any access, the AMF performs an AMF-initiated AM Policy Association Termination procedure.

7

The AMF sends NAS message Deregistration Accept to UE depending on the Deregistration type i.e. if Deregistration type is switch-off, AMF does not send Deregistration Accept message.

8

The gNB exchanges the N2 UE Context Release with the AMF.