[Conditional] new AMF to old AMF: Namf_Communication_RegistrationCompleteNotify ().
If the AMF has changed the new AMF notifies the old AMF that the registration of the UE in the new AMF is completed by invoking the Namf_Communication_RegistrationCompleteNotify service operation.
If the authentication/security procedure fails, then the Registration shall be rejected, and the new AMF invokes the Namf_Communication_RegistrationCompleteNotify service operation with a reject indication reason code towards the old AMF. The old AMF continues as if the UE context transfer service operation was never received.
If one or more of the S‑NSSAIs used in the old Registration Area cannot be served in the target Registration Area, the new AMF determines which PDU Session cannot be supported in the new Registration Area. The new AMF invokes the Namf_Communication_RegistrationCompleteNotify service operation including the rejected PDU Session ID and a reject cause (e.g. the S‑NSSAI becomes no longer available) towards the old AMF. Then the new AMF modifies the PDU Session Status correspondingly. The old AMF informs the corresponding SMF(s) to locally release the UE's SM context by invoking the Nsmf_PDUSession_ReleaseSMContext service operation.
See clause 18.104.22.168.3 for details of Namf_Communication_RegistrationCompleteNotify service operation.