Patent ID: 11146939

Abstract:
A method in a proxy call session control function, P-CSCF, of handling an unauthenticated emergency call originating from a roaming user equipment that is not attached to the P-CSCF. The P-CSCF receives a session initiation protocol (SIP) REGISTER request from the UE, where the REGISTER request relating to the emergency registration. The P-CSCF determines an IP address of the UE. The P-CSCF sends an identity query to a policy and charging rules function (PCRF) indicating the IP address of the UE and requesting other identifiers of the UE. The P-CSCF receives one or more other identifiers of the UE from the PCRF. The P-CSCF obtains a TEL and/or SIP uniform resource identifier (URI) for the UE on the basis of at least one of the one or more other identifiers. The P-CSCF sends a 200 OK response to the UE in response to the SIP REGISTER request, where the 200 OK response includes the TEL and/or SIP URI. Also provided are corresponding methods in other nodes and for authenticated emergency calls, and apparatus for implementing the methods.