Patent ID: 11924798
Assignee: NOKIA TECHNOLOGIES OY
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 14:
15. A method comprising:
during a registration update procedure between a user equipment (UE) and an access and mobility management function (AMF), receiving a registration request for an emergency services fallback request at the AMF, wherein a timer is started by the UE when the registration request is sent to the AMF;
in response to expiry of the timer, enabling an emergency services fallback attempt failure notification to be sent to upper layers of the UE by the AMY;
in response to the registration request being accepted by the AMF, enabling initiation of a service request procedure for emergency services fallback; and
in response to the registration request being rejected by the AMF, causing a registration reject response to the registration request to be provided to the UE to enable stopping of the timer in response to receipt of the registration reject response at the UE, indicating the emergency services fallback request has not been accepted and providing a predefined cause value, the predefined cause value indicating that an identity of a user equipment (UE) cannot be derived by a network, enabling initiation of (i) communication via a cell connected to an evolved packet core or a core network and (ii) a mobility management procedure.