Patent ID: 8041331
Filing Date: 2011-10-18
Classification: H04L

Abstract:
1. A method in a communications system comprising a network and a mobile communications device, the method performed by the mobile communications device comprising: maintaining a configuration of whether a message received by the mobile telecommunications device is permitted to trigger an emergency call setup, the configuration being non-configurable by the user of the mobile telecommunications device; sending a Session Initiation Protocol (SIP) INVITE request to the network comprising a Proxy Call Session Control Function (P-CSCF); receiving the message prompting an emergency call setup from a message source, the message being an alternative service message and including identification of the message source, the message having a body in an Extensible Markup Language (XML) including an <alternative service> element with the <type> child element set to “emergency”; when the received message is a response to the INVITE request, determining whether the message source is a trusted source based on the configuration and the identification of the message source in the response message; and attempting the emergency call setup only when the message source is a trusted source.