US 11,743,705 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. 17/246,930.
Application 17/246,930 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 2021/0258760 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 policy and charging rules function (“PCRF”) node to handle an internet protocol multimedia subsystem (“IMS”) emergency call, the method comprising:
receiving an identity request from a proxy call session control function (“P-CSCF”) of an IMS network, the identity request comprising an internet protocol (“IP”) address for a user equipment (“UE”);
responsive to receiving the identity request, determining one or more identifiers of the UE based on the IP address, the one or more identifiers being separate from the IP address, and the one or more identifiers comprising at least one of an international mobile subscriber identity (“IMSI”) and a mobile subscriber integrated digital network number (“MSISDN”);
responsive to determining the one or more identifiers, transmitting an indication of the one or more identifiers of the UE to the P-CSCF;
transmitting a resource allocation request to a packet data network gateway (“PGW”); and
responsive to transmitting the resource allocation request, receiving a resource allocation answer from the PGW indicating that resources for the IMS emergency call have been reserved.