Outbound Proxy Server for VoIP Emergency Call Location Routing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In voice-over-packet (VoP) networks, emergency services calls from mobile client devices often lack reliable location information, making it difficult for public safety answering points (PSAPs) to route calls accurately and dispatch assistance effectively, as the devices' mobility and dynamic connectivity disrupt the association between telephone numbers and fixed locations.
Innovation Solution
A method and system that utilize a voice-over-packet access network to obtain and provide network-provided location information for client devices, which is used to route emergency services calls to the appropriate PSAP, with an outbound proxy server receiving SIP INVITE messages, accessing a location database to determine the device's location, and inserting this information into the message to ensure accurate routing and dispatching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If client devices are allowed to move freely in VoP networks, then device mobility and connectivity flexibility are improved, but reliable location association for emergency call routing deteriorates
Solution Approach 1:
The patent introduces an outbound proxy server as an intermediary between the mobile client device and the PSAP routing system. This proxy server captures SIP INVITE messages, extracts location information from them, and uses this captured data to determine the appropriate PSAP. The intermediary approach allows the system to maintain reliable location tracking for emergency routing while preserving device mobility, as the proxy server obtains location data at the point of call initiation rather than relying on continuously updated device location reports.
2Reliability
If telephone numbers are associated with fixed locations in PSTN, then emergency call routing to appropriate PSAP is reliable, but adaptability to mobile devices in VoP networks deteriorates
Solution Approach 1:
Instead of associating location with the telephone number as in traditional PSTN, the patent inverts the approach by extracting location information directly from the SIP INVITE message itself. The outbound proxy server captures the location data embedded in the SIP message header and uses this information to determine PSAP routing. This inversion allows mobile devices to maintain reliable emergency routing without requiring fixed location association with their telephone numbers, as the location is dynamically obtained from each call's SIP message.
3Ease of operation
If client-provided location information is used, then device autonomy is improved, but location accuracy and reliability for emergency routing deteriorates due to mobility
Solution Approach 1:
The patent applies preliminary action by having the outbound proxy server capture and store location information from the SIP INVITE message at the very beginning of the call setup process. This captured location data is preserved and used for PSAP determination, rather than relying on location information that may change during the call. By performing the location capture action preliminarily at call initiation, the system ensures location accuracy is maintained despite device mobility during the emergency call.
Data Source
AI summary
A client device transmits, via a voice-over-packet (VoP) access network, a message that requests an emergency services call. An outbound proxy server receives the message and obtains a network-provided location of the client device, e.g., by looking up the source address of the message in a location database maintained by the access network or by invoking an active network location function. The outbound proxy server inserts the network-provided location into the message, leaving any client-provided location in the message undisturbed, and forwards the message to an emergency services routing server. The emergency services routing server determines which public safety answering point (PSAP) should receive the call, based on at least one of the network-provided location and any client-provided location in the message.