VoIP Call Fallback to PSTN via Automatic Network Switching
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Solution Overview
Problem
Existing voice call systems lack seamless transition from packet-switched networks to PSTN networks when connectivity is lost, requiring manual redialing and disrupting the call experience.
Innovation Solution
A mechanism where the near-end user terminal automatically detects packet-switched network failures and re-establishes the call via the PSTN network, using stored PSTN numbers or temporary gateway numbers, to ensure a seamless transition without user intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a packet-switched network (VoIP) is used for voice calls, then call cost is reduced and audio bandwidth is improved, but call reliability deteriorates when network connectivity is lost
Solution Approach 1:
The system performs preliminary actions by detecting packet-switched network connectivity status before call failure occurs. The client application continuously monitors network conditions and proactively switches to PSTN network before the call is completely lost, ensuring seamless transition and maintaining call continuity without user intervention.
Solution Approach 2:
The invention introduces an intermediary switching mechanism that acts as a bridge between packet-switched and circuit-switched networks. When packet-switched connectivity fails, this intermediary system automatically routes the call through alternative networks (PSTN, cellular, Wi-Fi), serving as a mediator that maintains call continuity across different network types without requiring user action.
2Loss of time
If manual redialing is required when packet-switched connectivity fails, then system complexity is reduced, but loss of time increases due to user intervention
Solution Approach 1:
The system implements self-service by enabling the client application to automatically detect packet-switched network failures and initiate fallback to alternative networks without user intervention. The application autonomously monitors connectivity, determines when switching is necessary, and executes the network transition, thereby eliminating manual redialing and reducing call restoration time.
Solution Approach 2:
The invention incorporates feedback mechanisms where the client application continuously monitors packet-switched network connectivity status and uses this feedback to automatically trigger fallback actions. When network quality degrades or connectivity is lost, the system receives feedback about the failed connection and automatically responds by switching to alternative networks, ensuring minimal interruption to the call.
3Ease of operation
If automatic PSTN fallback is implemented, then call reliability is improved during network failures, but device complexity increases
Solution Approach 1:
The client application is designed with multi-functionality to operate across multiple network types (packet-switched, circuit-switched, Wi-Fi, cellular). This universal design allows the application to seamlessly switch between different network infrastructures without requiring separate applications or complex user configuration, thereby improving ease of operation while managing device complexity through a unified multi-network interface.
Data Source
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AI summary
A method of controlling a call between first and second user terminals, the method comprising: during the call, detecting a failure of a connection between the first user terminal and a packet-switched network; and in response, causing the call to be conducted at least part way via a PSTN network, via a connection between the first user terminal and the PSTN network. The call may be initiated by the first user terminal (such that the first user terminal is the caller and the second is the callee). The call may be initially conducted, prior to the failure, via a packet-switched connection between the first user terminal and a packet-switched network. The method may be implemented by a client application run on the first user terminal. Alternatively the method may be implemented by a server.