Emergency Call UA Address Mapping for Circuit-Switched Callbacks
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Solution Overview
Problem
In the context of IMS emergency calls, there is a challenge in translating packet-switched UA identifiers into addresses recognizable by circuit-switched PSAPs, which are necessary for callback and location information retrieval, due to differences in addressing schemes between packet-switched and circuit-switched domains.
Innovation Solution
The solution involves associating packet-switched addresses of UAs with temporary E.164 numbers, specifically tel URIs, which can be used in circuit-switched networks, and maintaining a mapping between these temporary tel URIs and UA packet-switched addresses within the network, allowing reuse and efficient retrieval of information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If packet-switched UA identifiers are translated into circuit-switched addresses for emergency calls, then callback capability and location retrieval are enabled, but the complexity of addressing scheme translation increases
Solution Approach 1:
The patent introduces a mapping table as an intermediary data structure that stores correlations between packet-switched UA identifiers (SIP URIs, GRUUs) and circuit-switched E.164 numbers. This mapping table acts as a mediator that translates addresses between the two domains without requiring complex real-time translation logic, thereby enabling reliable callback while managing translation complexity through pre-established mappings.
Solution Approach 2:
The system performs preliminary action by pre-establishing and storing address mappings in the mapping table before emergency calls occur. The correlation between packet-switched and circuit-switched addresses is recorded in advance, allowing the PSAP to quickly retrieve callback information without performing complex translation during the emergency response process.
2Adaptability or versatility
If temporary E.164 numbers are allocated to packet-switched UAs for emergency calls, then circuit-switched network compatibility is achieved, but the depletion of available temporary URIs occurs
Solution Approach 1:
The patent implements discarding and recovering by allowing temporary E.164 numbers to be discarded after their associated emergency calls are completed, and then recovered back into the pool of available temporary URIs for reuse. The mapping table maintains the correlation between temporary E.164 numbers and packet-switched addresses, enabling the system to recycle these resources rather than permanently allocating them, thus preventing depletion while maintaining circuit-switched compatibility.
3Reliability
If address mapping information is stored in the network for later retrieval, then callback functionality is enabled, but the storage and retrieval complexity increases
Solution Approach 1:
The patent extracts the address mapping information from the complex translation process and stores it separately in a dedicated mapping table. This extraction isolates the storage and retrieval operations from the main call processing logic, allowing the system to maintain simple retrieval procedures while enabling reliable callback functionality through pre-stored correlations between packet-switched and circuit-switched addresses.
Data Source
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AI summary
A method is provided for identifying a device during an emergency for callback. The method includes storing an address of a user agent (UA) during initiation of an emergency call by the UA, associating an E.164 number with the stored address of the UA that placed the emergency call, and routing the emergency call containing the E.164 number.