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

Claim 0:
1. A method comprising:
during a registration update procedure between a user equipment (UE) and an access and mobility management function (AMF), causing a registration request to be sent for an emergency services fallback request;
starting a timer when the registration request is sent;
in response to expiry of the timer, causing 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, initiating 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) stopping the timer, (ii) initiating communication via a cell connected to an evolved packet core or a core network, and (iii) initiating a mobility management procedure.