Telefonaktiebolaget LM Ericsson (publ)
IMS emergency calls for roaming UEs

Abstract:

A method in a proxy call session control function, P-CSCF, of handling an unauthenticated emergency call originating from a roaming user equipment, UE, which is not attached to the P-CSCF. The P-CSCF receives a SIP INVITE request from the UE, the INVITE request relating to the unauthenticated emergency call, and 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, and receives one or more other identifiers of the UE from the PCRF. The P-CSCF constructs a TEL and/or SIP uniform resource identifier, URI, for the UE on the basis of at least one of said other identifiers, inserts the URI into the SIP INVITE request, and sends the SIP INVITE request to a public safety answering point, PSAP. Also provided are corresponding methods in other nodes and for authenticated emergency calls, and apparatus for implementing the methods.