PSAP Callback Identification via Information Element in IMS Emergency Services
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Solution Overview
Problem
Public safety answering points (PSAP) face challenges in ensuring callbacks from emergency calls reach the correct device, as existing systems treat callbacks as normal calls and may be subject to services like call forwarding, making it difficult to identify the emergency caller by network and device.
Innovation Solution
A method involving a wireless transmit/receive unit (WTRU) in one network transmitting a registration message to a serving call session control function (S-CSCF) in another network, storing an information element (IE) received, and including it in emergency calls to ensure callbacks from PSAPs, whether in IP or PSTN networks, reach the appropriate device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PSAP callbacks are treated as normal incoming calls, then standard call handling services are applied, but the callback may be interfered with by services like call forwarding and fail to reach the emergency caller
Solution Approach 1:
The patent segments the call handling process by introducing a distinct identification mechanism for emergency callbacks. The Information Element (IE) acts as a separate identifier that distinguishes emergency callbacks from normal calls, allowing the system to apply different handling rules without complicating the overall call management architecture.
Solution Approach 2:
The Information Element (IE) serves as an intermediary mechanism between the PSAP and the WTRU. This IE carries identification information that enables the network to recognize and properly route emergency callbacks to the correct device, acting as a mediator that facilitates reliable delivery without requiring complex system-wide changes.
2Measurement precision
If emergency caller identification is not implemented, then the system operates with standard call routing, but it becomes difficult to determine which device placed the emergency call
Solution Approach 1:
The system performs preliminary action by including the Information Element (IE) with identification information in the initial emergency call setup. This pre-established identifier ensures that when the PSAP needs to callback, the network can immediately identify the correct WTRU without losing the emergency call information or requiring complex identification procedures later.
Data Source
AI summary
A method and apparatus for identifying public safety answering point (PSAP) callbacks by transmitting, by a wireless transmit/receive unit (WTRU) in a first network, a registration message, to a PSAP in a second network. Upon registration, the WTRU receives a registration response including an information element (IE) and stores the IE. The PSAP, which may be located in either an internet protocol (IP) Network or a public switched telephone network (PSTN), transmits an emergency callback to the WTRU and includes the IE.