US 11,917,516 B2
Internet protocol multimedia subsystem emergency calls for roaming user equipments
Fredrik Lindholm, Tokyo (JP); Ralf Keller, Würselen (DE); Susana Fernandez Alonso, Madrid (ES); and Ivo Sedlacek, Hovorcovice (CZ)
Assigned to TELEFONAKTIEBOLAGET LM ERICSSON (PUBL), Stockholm (SE)
Filed by Telefonaktiebolaget LM Ericsson (publ), Stockholm (SE)
Filed on May 3, 2021, as Appl. No. 17/246,796.
Application 17/246,796 is a continuation of application No. 16/415,119, filed on May 17, 2019, granted, now 11,146,939.
Application 16/415,119 is a continuation of application No. 15/558,890, granted, now 11,032,688, previously published as PCT/EP2015/057265, filed on Apr. 1, 2015.
Prior Publication US 2021/0258759 A1, Aug. 19, 2021
This patent is subject to a terminal disclaimer.
Int. Cl. H04W 4/90 (2018.01); H04W 76/50 (2018.01); H04L 65/1016 (2022.01); H04L 65/1069 (2022.01); H04W 60/00 (2009.01); H04L 65/1073 (2022.01); H04L 65/1104 (2022.01); H04M 3/51 (2006.01); H04W 80/10 (2009.01); H04W 8/20 (2009.01); H04W 92/02 (2009.01); H04W 12/06 (2021.01); H04W 12/72 (2021.01); H04L 65/1045 (2022.01)
CPC H04W 4/90 (2018.02) [H04L 65/1016 (2013.01); H04L 65/1069 (2013.01); H04L 65/1073 (2013.01); H04L 65/1104 (2022.05); H04W 60/00 (2013.01); H04W 76/50 (2018.02); H04L 65/1045 (2022.05); H04M 3/5116 (2013.01); H04W 8/20 (2013.01); H04W 12/06 (2013.01); H04W 12/72 (2021.01); H04W 80/10 (2013.01); H04W 92/02 (2013.01)] 20 Claims
OG exemplary drawing
 
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.