Patent ID: 11917516
Assignee: TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A method of operating a user equipment (“UE”) to handle an internet protocol multimedia subsystem (“IMS”) emergency call, the method comprising:
sending a session initiation protocol (“SIP”) REGISTER request relating to an emergency registration to a proxy call session control function (“P-CSCF”) of an IMS network;
responsive to sending the SIP REGISTER request, receiving a 200 OK response from the P-CSCF including at least one of:
a telephone (“TEL”) uniform resource identifier (“URI”) based on one or more identifiers that includes a mobile subscriber integrated services digital network number (“MSISDN”) and does not include an international mobile subscriber identity (“IMSI”); and
a SIP URI for the UE based on a mobile network code (“MNC”), a mobile country code (“MCC”), and global E.164 number conversion of the MSISDN; and

responsive to receiving the response, performing an action based on the response.