Intelligent IP Phones for Reliable E-911 Services
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Solution Overview
Problem
IP-based PBX systems face challenges in providing accurate and reliable E-911 services due to issues with location precision, ELIN-DID mapping, and network fluidity, leading to potential disruptions and difficulties in maintaining accurate location information during emergency calls.
Innovation Solution
The method involves intelligent IP phones that store necessary information for initiating 911 calls, including ERL identifiers and ELINs, allowing them to directly communicate with a PSTN gateway, bypassing traditional call signaling components, and utilizing a location server for accurate location determination and network management integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional IP Call Processing networks are used for E-911 services, then system complexity is reduced, but reliability deteriorates due to potential inter-site link failures and network fluidity issues
Solution Approach 1:
The patent extracts the critical E-911 signaling path from the IP Call Processing network by enabling direct SIP signaling between IP phones and PSTN gateways. This removes the dependency on intermediate IP network elements and inter-site links for emergency calls, thereby improving reliability without significantly increasing overall system complexity.
Solution Approach 2:
The patent introduces a location server as an intermediary that provides centralized location information management. This mediator resolves the conflict between network fluidity and location accuracy by maintaining authoritative location data that can be queried by gateways, ensuring reliable E-911 service regardless of network changes.
2Reliability
If IP phones directly communicate with PSTN gateways for emergency calls, then reliability improves by bypassing IP Call Processing networks, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring IP phones with the necessary SIP signaling capabilities and location information during initialization. The phones are pre-provisioned with gateway addresses and location data, enabling them to immediately initiate direct emergency calls without requiring complex runtime decision-making or additional processing complexity.
3Measurement precision
If centralized location information management is implemented, then location accuracy improves, but network dependency increases
Solution Approach 1:
The location server acts as a dedicated intermediary that centralizes location information management. It receives location data from the network management system and provides it to PSTN gateways upon request. This mediator approach improves location accuracy while isolating the complexity of location tracking from both the phones and gateways, as they only need to interact with the simplified location server interface.
Data Source
AI summary
Providing enhanced emergency services (E-911) to an IP Telephony-based PBX or similar system, by utilizing aspects of the intelligence of end-user SIP client devices to address challenges and difficulties associated with E-911-like services in LAN-based telephony environments.