When the UDM stores the associated Access Type (e.g. 3GPP) together with the serving AMF as indicated in step 14a, it will cause the UDM to initiate a Nudm_UECM_DeregistrationNotification (see clause 188.8.131.52.2) to the old AMF corresponding to the same (e.g. 3GPP) access, if one exists. If the timer started in step 5 is not running, the old AMF may remove the UE context. Otherwise, the AMF may remove UE context when the timer expires. If the serving NF removal reason indicated by the UDM is Initial Registration, then, as described in clause 184.108.40.206.2, the old AMF invokes the Nsmf_PDUSession_ReleaseSMContext (SUPI, PDU Session ID) service operation towards all the associated SMF(s) of the UE to notify that the UE is deregistered from old AMF. The SMF(s) shall release the PDU Session on getting this notification.
If the old AMF has established a Policy Association with the PCF, and the old AMF did not transfer the PCF ID(s) to the new AMF (e.g. new AMF is in different PLMN), the old AMF performs an AMF-initiated Policy Association Termination procedure, as defined in clause 220.127.116.11, to delete the association with the PCF. In addition, if the old AMF transferred the PCF ID(s) in the UE context but the new AMF informed in step 10 that the AM Policy Association information in the UE context will not be used then the old AMF performs an AMF-initiated Policy Association Termination procedure, as defined in clause 18.104.22.168, to delete the association with the PCF.
If the old AMF has an N2 connection for that UE (e.g. because the UE was in RRC Inactive state but has now moved to E-UTRAN or moved to an area not served by the old AMF), the old AMF shall perform AN Release (see clause 4.2.6) with a cause value that indicates that the UE has already locally released the NG-RAN's RRC Connection.