Subscriber Emulator Routing Circuit Switched Calls to Packet Network Services
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Solution Overview
Problem
Legacy circuit-switched telephony networks have limited ability to provide enhanced services for circuit-switched calls, and there is a need to offer these services from a packet network without requiring significant modifications to existing telephony switches.
Innovation Solution
A subscriber emulator intercepts and routes calls between a telephony switch and a service node in a packet network, allowing the service node to provide enhanced services such as advanced call routing, call screening, and presence systems, while maintaining compatibility with legacy switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If enhanced services are provided directly from the circuit-switched network, then service capability is improved, but device complexity and modification requirements increase
Solution Approach 1:
A service node is introduced as an intermediary component between the circuit-switched network and packet-switched services. The service node receives service requests from the circuit-switched network, processes them using packet network capabilities, and returns results without requiring modifications to existing telephony switches. This mediator approach enables enhanced services while maintaining compatibility with legacy infrastructure.
2Adaptability or versatility
If legacy telephony switches are modified to support enhanced services, then service functionality is improved, but ease of manufacture and deployment deteriorates
Solution Approach 1:
The service provisioning architecture is segmented into distinct functional components: the existing circuit-switched telephony switch, a gateway interface, and a separate service node in the packet network. This segmentation allows the service enhancement functionality to be deployed independently as a separate system rather than requiring integration into legacy switch hardware or software, greatly simplifying deployment.
3Reliability
If circuit-switched networks use TDM bearer paths, then call processing reliability is maintained, but adaptability to packet-based services deteriorates
Solution Approach 1:
A gateway is positioned as an intermediary between the TDM bearer path circuit-switched network and the packet-switched service node. The gateway performs protocol conversion and signal translation, allowing reliable TDM-based call processing to coexist with and access packet-based enhanced services. This mediator enables dual compatibility without compromising the reliability of existing call processing.
Data Source
AI summary
The present invention relates to providing services for circuit-switched calls from an Internet Protocol (IP) based packet network. In essence, a call originating from or intended for a subscriber that is served by a telephony switch, such as an end office or mobile switching center, in a circuit-switched network is intercepted and routed by the telephony switch to a service node via a subscriber emulator. The subscriber emulator acts as a liaison between the telephony switch of the circuit-switched network and the service node of the packet network. Preferably, the subscriber emulator presents itself to the service node as a user agent, which acts on behalf of a subscriber that is served the telephony switch. The service node provides any requisite processing of the call to implement services for the call.