Patent ID: 9515850
Filing Date: 2016-12-06
CPC Classification: H04L,H04M,H04W

Claim Text:
1. A method for completing an emergency call in an all Internet Protocol (IP) network having GPRS access, the method comprising: implementing, in a node in the IP network, a pool of stored, substitute Subscriber Identity Modules (SIMs) that are designated as an Emergency SIM Pool Function (ESPF); receiving, at the node, an initial emergency call request message from a User Equipment (UE) with no SIM card or an invalid SIM card, the node being remote from the UE; presenting the initial emergency call request message to the UE's home network HLR; upon rejection of the initial emergency call request message as invalid, the ESPF intercepting a subsequent emergency call request message from the UE, the subsequent emergency call request message including an emergency IMSI formed by concatenating a portion of the International Mobile Equipment Identity (IMEI) of the UE with the subsequent emergency call request; substituting a valid IMSI for the emergency IMSI using a SIM from the ESPF; forwarding the subsequent emergency call request message with the valid IMSI to the IP network's HLR, wherein the valid IMSI is authenticated; and completing the emergency call by routing the authenticated emergency request message to a Public Safety Answering Point.