E-CSCF Identifier Routing for Emergency Call Trunk Management
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Solution Overview
Problem
Emergency call management systems face challenges in efficiently routing E911 calls due to limited trunk allocations and the need to differentiate between legitimate and false emergency calls, particularly in IP Multimedia Subsystem networks.
Innovation Solution
The implementation of a Media Gateway Control Function (MGCF) and Emergency Call Session Control Function (E-CSCF) identifiers within SIP requests, allowing the MGCF to recognize and route E911 calls correctly, while preventing false calls by verifying the presence of specific identifiers in SIP headers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If limited E911 trunks are allocated in Time Division Multiplexing-based systems, then network resource efficiency is improved, but the ability to handle emergency calls reliably deteriorates
Solution Approach 1:
The patent introduces the E-CSCF as an intermediary function that sits between the IMS core network and the E911 trunk gateway. This intermediary validates emergency call requests, adds identifying headers, and mediates the connection to limited E911 trunks. By centralizing this validation and routing function, the system can reliably manage limited trunk resources while maintaining high availability for legitimate emergency calls.
Solution Approach 2:
The patent implements preliminary validation of emergency call requests before they reach the E911 trunk gateway. The E-CSCF performs preliminary checks to verify the call is indeed an emergency call and adds identifying headers in advance. This preliminary action prevents false calls from consuming limited trunk resources, thereby improving both trunk utilization efficiency and routing reliability.
2Ease of operation
If emergency call validation is simplified, then ease of operation is improved, but the ability to prevent false calls deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the E-CSCF validates emergency call requests and provides feedback information through SIP headers to the calling party and network elements. The system monitors call patterns and can provide feedback to identify and block false calls while maintaining simple operation for legitimate calls. This feedback loop enables intelligent differentiation without complicating the user experience.
3Object-affected harmful factors
If identifier verification is implemented in SIP headers, then false call prevention is improved, but device complexity increases
Solution Approach 1:
The patent makes the E-CSCF and MGCF components multi-functional by having them perform both standard IMS call routing functions and specialized E911 validation functions. The same E-CSCF that handles general emergency call routing also performs identifier verification and adds E911-specific headers. This universality reduces overall system complexity by consolidating functions rather than requiring separate dedicated components for each function.
Data Source
AI summary
A system that incorporates teachings of the present disclosure may include, for example, a network element operably couplable to an Internet Protocol Multimedia Subsystem network where the network element has a controller to receive an SIP request associated with a call, determine whether the SIP request comprises an identifier associated with an Emergency Call Session Control Function (E-CSCF) where the identifier was added to the SIP request by the E-CSCF, and provide the call to an emergency network when the identifier is associated with the E-CSCF. Other embodiments are disclosed.