Telephony services in mobile IP networks

摘要

An emergency telephone call is supported and routed to a Public Safety Answering Point (PSAP) in an IP based packet switched wireless communications network. An activate PDP context request is sent from a user equipment to the network. A parameter in the activate PDP context request indicates that the PDP context will be used to transfer an emergency call. An activate PDP context accept message is returned from the support node to the user equipment. The activate PDP context accept message acknowledges the activate PDP context request message and provides the address of a call state control function. A call setup request transferred to the call state control function includes the Service Area Identity (SAI). The call state control function selects a PSAP based, at least in part, on the SAI included in the call setup request and forwards the emergency call to the selected PSAP.