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

Claim 7:
8. An apparatus comprising:
at least one processor; and
at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to:
during a registration update procedure between a user equipment (UE) and an access and mobility management function (AMF), cause a registration request to be sent for an emergency services fallback request;
start a timer when the registration request is sent;
in response to expiry of the timer, cause an emergency services fallback attempt failure notification to be sent to upper layers of the UE;
in response to the registration request being accepted by the network entity, initiate a service request procedure for emergency services fallback;
in response to receipt of a registration reject response, comprising a predefined cause value indicating that an identity of the UE cannot be derived by a network, to the registration request, (i) stop the timer, (ii) initiate communication via a cell connected to an evolved packet core or a core network, and (iii) initiate a mobility management procedure.