Patent ID: 11930549
Assignee: SHARP KABUSHIKI KAISHA
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 1:
2. A communication control method performed by a User Equipment (UE), the communication control method comprising:
performing a second emergency call attempt in an Evolved Packet System (EPS) in a case of a failure of a first emergency call attempt in a 5G system (5GS);
receiving a Protocol Data Unit (PDU) SESSION ESTABLISHMENT REJECT message as the failure of the first emergency call attempt;
determining whether the system in which the UE performs the second emergency call attempt is the EPS or the 5GS, based on a cause value indicating a reason that the first emergency call attempt is rejected;
using a first access network for the first emergency call attempt; and
using a second access network for the second emergency call attempt.