Emergency Call Recovery via SIP Session Bridging
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Solution Overview
Problem
Existing emergency call systems face challenges in quickly re-establishing disrupted calls between callers and operators without user intervention, particularly when application servers fail, leading to dropped connections and potential confusion or wasted time in relaying emergency information.
Innovation Solution
Implementing a method and apparatus that utilize a Session Initiation Protocol (SIP) messaging session re-establishment process, involving a recovery queue and backup servers to automatically reconnect call legs, ensuring seamless continuation of emergency calls without user interaction, even if the initial call answer node fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the operator attempts to re-establish the call by calling back to the caller's number, then the call can be re-connected, but it requires additional time and caller intervention
Solution Approach 1:
The system stores call leg information and maintains session state in a recovery queue before the call needs to be re-established. When a call drops, the pre-stored information enables immediate re-establishment without requiring caller intervention or additional setup time, thus resolving the contradiction between reliability and time loss.
2Reliability
If the operator calls back to re-establish the call, then connection can be restored, but it requires the caller to hang up and answer again
Solution Approach 1:
The system automatically re-establishes dropped calls using stored call leg information and recovery queue data without requiring the caller to take any action. The network infrastructure itself performs the re-establishment service, eliminating the need for caller intervention and improving ease of operation while maintaining reliability.
3Reliability
If a backup answer node is used to re-establish calls, then call continuity is maintained, but system complexity increases
Solution Approach 1:
The primary answer node acts as an intermediary that pre-processes and stores call leg information in a recovery queue before potential failure occurs. This intermediary function enables the backup node to quickly assume the call without complex real-time coordination, maintaining call continuity while managing system complexity through structured information preservation.
Data Source
AI summary
A system, method and apparatus for re-establishing a messaging session received at a public safety answering point are described. A Session Initiation Protocol (SIP) messaging session establishment request is received at an emergency call answer node. The messaging session establishment request has an indication of a previously established emergency messaging session between an operator workstation and a sending device to re-establish. The emergency call answer node checks a recovery queue for a previously received call establishment request having a matching indication for the previously established messaging session to re-establish. The emergency call answer node bridges a session leg for the received call establishment request and, a session leg for the previously received call establishment request having the matching indication for the previously established messaging session to re-establish the messaging session when a match is found.