VoIP Call Forwarding for Unreachable Terminals
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Solution Overview
Problem
Existing communication technologies face challenges in establishing call connections when a called terminal is in an area with poor or no signal coverage, or when it is in an airplane mode or dual-card single-pass scenario.
Innovation Solution
A call method and system that includes a first terminal device, a network device, a VoIP server, and a second terminal device with a VoIP client. When the called terminal is unreachable, the network device forwards the call request to the VoIP server, which initiates a VoIP call to the second terminal device, ensuring the call request is received even in out-of-service states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the called terminal uses traditional cellular network for call reception, then call connection can be established in normal signal areas, but call connection fails in areas with poor or no signal coverage
Solution Approach 1:
The patent introduces a VoIP server as an intermediary between the calling terminal and the called terminal. When the called terminal is in a poor signal area or airplane mode and cannot receive traditional cellular calls, the network device forwards the call request to the VoIP server, which then establishes a VoIP call to the called terminal's data connection. This intermediary approach allows calls to succeed despite poor cellular signal conditions.
Solution Approach 2:
The patent changes the communication parameter from traditional cellular voice channel to VoIP data channel. By switching the call protocol from circuit-switched cellular voice to packet-switched VoIP over data connection, the system bypasses the signal strength limitation of cellular voice and utilizes the more robust data connection even in poor signal areas.
2Object-affected harmful factors
If the called terminal is in airplane mode, then power consumption is reduced and interference minimized, but call requests cannot be received
Solution Approach 1:
The VoIP server acts as a mediator that receives call requests through the cellular network and delivers them to the called terminal via data connection. Even when the terminal is in airplane mode with cellular radio off, the data connection (Wi-Fi or mobile data) remains active, allowing the VoIP server to deliver calls through this alternative path.
Solution Approach 2:
The patent segments the communication path into two independent channels: cellular control channel for call request delivery and data connection for actual voice transmission. This segmentation allows the terminal to maintain data connection while disabling cellular radio in airplane mode, enabling call reception through the data channel via VoIP.
3Device complexity
If dual-card single-pass audio is used to share radio frequency resources, then device complexity is reduced, but simultaneous call reception on both cards is impossible
Solution Approach 1:
The patent changes the communication parameter for the second card from cellular voice channel to VoIP data channel. When one card is in a call and cannot receive calls due to single-pass audio limitation, the other card can still receive VoIP calls over data connection, providing call availability without requiring dual radio frequency resources.
Data Source
AI summary
This application discloses a call method and system, and a related apparatus. When a specific condition is met (for example, a callee fails to be paged), a network device forwards, to a VoIP server, a first call request to a target number, where the first call request is a call request initiated by a calling terminal to the target number, and the target number has been subscribed to a call forwarding service. Then the VoIP server parses a forwarding message from the network device to obtain a called number, searches, based on the called number, for the called terminal associated with the called number, and initiates a VoIP call to the called terminal, so that the callee in an out-of-service state (for example, there is no signal of an operator network or the callee is in an airplane mode) can still receive the call request from the caller.