IMS Late Call Forwarding via ICCF Intermediary Control
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Solution Overview
Problem
The existing IMS centralized service lacks a complete solution for late call forwarding, particularly for user-determined user busy, no paging response, and no answer scenarios.
Innovation Solution
A late call forwarding method is implemented in the IMS centralized service, where the ICCF receives a call request, acquires the called user's roaming number, and initiates a call to trigger late call forwarding if the user subscribes to the service and meets specific conditions, involving message exchanges between the VMSC, ICCF, and TAS to inform and initiate forwarding services.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the IMS centralized service is implemented without late call forwarding solution, then the basic centralized service functionality is provided, but the call forwarding service completeness deteriorates
Solution Approach 1:
The patent introduces the ICCF as an intermediary component between the VMSC and the TAS. The ICCF receives call requests from the VMSC, determines whether late call forwarding should be triggered based on user status, and then initiates corresponding forwarding services. This intermediary architecture enables complete call forwarding functionality without requiring complex modifications to existing network elements.
2Manufacturing precision
If late call forwarding is triggered by user status conditions, then the call forwarding accuracy is improved, but the signaling message complexity increases
Solution Approach 1:
The patent implements preliminary actions by having the VMSC determine user status conditions (such as user busy, no answer, or unreachable states) before initiating the call forwarding process. The ICCF then uses these pre-determined conditions to accurately trigger appropriate forwarding services, avoiding the need for complex real-time decision-making and reducing signaling overhead.
3Reliability
If the VMSC triggers late call forwarding service, then the forwarding service reliability is improved, but the network control complexity increases
Solution Approach 1:
The patent segments the call forwarding control function into distinct modules: the VMSC handles user status determination and service triggering, the ICCF handles forwarding decision-making and service initiation, and the TAS handles specific forwarding service execution. This segmentation allows each component to perform its function reliably while maintaining manageable control complexity through clear functional boundaries.
Data Source
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Figure 3
AI summary
The present invention discloses a late call forwarding method in the IMS centralized service. During a call setting up, an ICCF in the IMS circuit switching domain receives a call request from the CSCF serving the called user, which is referred to as session A, and the ICCF acquires a called user's roaming number and initiates a call to the called user, which is called session B. After the VMSC serving the called user receives the call request, if it determines that the status of the called user satisfies conditions for triggering the late call forwarding and the called user subscribes the late call forwarding service and is equipped with a calling intelligent trigger, it triggers the late call forwarding service. A CAMEL service is triggered when the VMSC initiates a call to the forwarding target. The VMSC exchanges messages with the ICCF and informs the ICCE about session associated information and the forwarding reason. When the ICCF determines that the forwarding is needed, it sends a response to the session A including a corresponding indication or does not send the response message according to the forwarding reason, after a telecom application server (TAS) receives the indication, the TAS initiates a regular forwarding service.