Patent ID: 9380609
Filing Date: 2016-06-28
CPC Classification: H04L,H04M,H04W

Claim Text:
1. A method for wireless communication, comprising: initiating a call attempt in an internet protocol multimedia subsystem (IMS) based on a dialed number, the dialed number comprising an emergency number; receiving a session initiation protocol (SIP) message in response to the call attempt; and determining in response to the SIP message whether to retry the call attempt as a normal call in a circuit-switched (CS) domain for an operator or as an emergency call in the CS domain for the operator, wherein the determining is based at least in part on either an indication in the SIP message or on a characteristic of the operator, wherein the characteristic comprises a Mobile Country Code (MCC) and a Mobile Network Code (MNC) for the operator, and the method further comprises: retrying the call attempt as the emergency call in the CS domain if the dialed number is available and is included in a local emergency number list received from the CS domain; retrying the call attempt as the emergency call in the CS domain if the dialed number is not available; retrying the call attempt as the emergency call in the CS domain if the dialed number is available and is not included in the local emergency number list received from the CS domain, and if the MCC or the MCC/MNC matches an MCC of a country or an MCC/MNC of an operator that requires a CS emergency call in response to the SIP message; and retrying the call attempt as the normal call in the CS domain if the dialed number is available and is not included in the local emergency number list received from the CS domain, and if the MCC or the MCC/MNC does not match the MCC of a country or the MCC/MNC of an operator that requires a CS emergency call in response to the SIP message.