AGCF and AGF Gateway for PSTN to IMS Signal Conversion
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Solution Overview
Problem
The existing telecommunication service networks, particularly those based on PSTN/ISDN, face challenges in flexibility, high deployment and extension costs, service conflicts, and limited mobility due to the coupling of call and service control functions in softswitch nodes, which hinders the integration of PSTN/ISDN services with IMS systems.
Innovation Solution
A system and method that include an Access Gateway Control Function (AGCF) and an Access Gateway Function (AGF) to convert between circuit domain and packet domain signals, enabling PSTN/ISDN terminals to access IMS services by converting narrowband voice and user interface signaling, and implementing access management and call control, allowing PSTN/ISDN services to be controlled and provided within the IMS framework.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PSTN/ISDN services are implemented in a circuit switched domain, then service reliability is maintained, but service flexibility and adaptability deteriorate
Solution Approach 1:
The patent segments the service implementation by introducing a service gateway that separates circuit domain access from packet domain core network. The service gateway divides functionality into access adaptation layer and core network layer, allowing circuit switched services to be delivered through packet switched infrastructure, thus maintaining reliability while improving flexibility.
Solution Approach 2:
The service gateway acts as an intermediary between the circuit switched access network and the packet switched core network. It translates and adapts signals between different domains, enabling PSTN/ISDN services to access IMS networks without direct integration, thereby preserving service reliability while enabling adaptability to packet domain.
2Adaptability or versatility
If softswitch architecture is used to implement PSTN/ISDN services in packet domain, then service adaptability improves, but device complexity increases
Solution Approach 1:
The patent extracts the circuit domain adaptation functionality from the core softswitch architecture and places it in a dedicated service gateway. This separation removes complexity from the core network elements while maintaining service adaptability at the gateway level, allowing the softswitch to focus on packet domain operations.
Solution Approach 2:
The service gateway introduces a new dimensional layer between access and core network, handling circuit-to-packet translation in this intermediate dimension. This allows the core softswitch to operate purely in packet domain without direct circuit domain complexity, reducing device complexity while maintaining adaptability.
3Ease of manufacture
If call control and service control functions are coupled in softswitch nodes, then implementation simplicity is maintained, but service deployment efficiency deteriorates
Solution Approach 1:
The patent segments control functions by separating call control (handled by IMS core network elements like CSCF) from service control (handled by service gateway). This functional segmentation enables independent deployment and modification of service logic without affecting core call control, significantly improving service deployment efficiency while maintaining implementation simplicity through standardized interfaces.
4Reliability
If PSTN/ISDN services are distributed in call processing nodes, then service autonomy is maintained, but network coordination capability deteriorates
Solution Approach 1:
The patent merges multiple distributed call processing nodes into a unified service gateway that handles circuit domain access. This consolidation maintains service autonomy through modular service logic while improving network coordination capability by providing a single coordination point for packet domain resources, enabling better resource management and service coordination.
Data Source
AI summary
Embodiments of the present invention disclose a system and a method for processing a packet domain service signal, which enable a terminal that does not support an access control protocol of an Internet Protocol Multimedia Subsystem (IMS) to access the IMS and acquire the services in the IMS. An AGCF is added for shielding the differences of the users on the basis of the IMS defined in the 3GPP R5/R6 standard, specifically, a PSTN/ISDN user accesses an AGF first, accesses the IMS through an agent function of the AGCF, and the AGCF also manages and controls the AGF. Control of the PSTN/ISDN services may be implemented in the AGCF, or in an AS added to the IMS, or the control of basic services and supplementary services may be implemented in the AGCF while the control of value-added services may be implemented in the AS.