Midcall Fallback for VoIP Calls via Call Agent
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Solution Overview
Problem
Voice over Internet Protocol (VoIP) calls are prone to disruptions due to deteriorating Internet connection quality, leading to delays, gaps, or packet loss, which existing technologies fail to effectively mitigate during ongoing calls.
Innovation Solution
Implementing a midcall fallback mechanism that switches a VoIP call from an IP network to a Public Switched Telephone Network (PSTN) when connection quality deteriorates, using a call agent to validate and establish a PSTN call by comparing calling party numbers to direct inward dialing (DID) numbers, ensuring seamless conversation continuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a VoIP call is established over the Internet, then cost and flexibility are improved, but connection reliability deteriorates due to packet loss and quality deterioration
Solution Approach 1:
The system performs preliminary actions by establishing a PSTN call in advance before the VoIP call quality deteriorates completely. The call agent monitors VoIP call quality and proactively sets up a fallback PSTN call path, ensuring that when packet loss or quality issues occur, the call can be seamlessly transferred to the pre-prepared PSTN connection, thereby maintaining connection reliability.
Solution Approach 2:
The call agent acts as an intermediary between the VoIP and PSTN networks. It monitors the quality of the VoIP call and mediates the transfer of the call from the IP network to the PSTN network when quality deteriorates. This intermediary function allows the system to leverage both networks' strengths while mitigating their individual weaknesses, improving overall connection reliability.
2Reliability
If midcall fallback from VoIP to PSTN is implemented, then connection reliability is improved, but device complexity increases due to dual network monitoring and switching
Solution Approach 1:
The call agent is designed with multi-functionality, serving both VoIP and PSTN networks through a single device. It can initiate, monitor, and manage calls on both networks, and perform the fallback switching function. This universal design consolidates what would otherwise require separate systems, reducing overall device complexity while maintaining call continuity.
Solution Approach 2:
The call agent autonomously monitors VoIP call quality and automatically initiates the fallback to PSTN when quality thresholds are breached, without requiring manual intervention. This self-service capability simplifies the system architecture by eliminating the need for additional control systems or user interfaces for managing the fallback mechanism.
3Reliability
If PSTN validation is performed by comparing CGPN to DID number, then security is improved, but processing time increases due to validation overhead
Solution Approach 1:
The system performs preliminary validation by pre-establishing the association between DID numbers and CGPNs during call setup. The call agent stores this mapping information in advance, so when fallback to PSTN is needed, the validation can be performed by simple lookup rather than complex real-time comparison, reducing processing time while maintaining security.
Data Source
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AI summary
A method for performing midcall fallback is provided. The method includes assigning a direct inward dialing (DID) number to a first client. The DID number may be selected from a list of direct inward dialing numbers. The method may further include establishing a VoIP phone call between the first client and a second client and sending a DID number representing the first client and receiving a dial sequence identifying a call agent serving the second client. The dial sequence may define a phone number to be dialed to reach the call agent. The method may also include determining that mid-call fallback should be performed, and performing midcall fall back, midcall fallback including establishing a public switched telephone network (PSTN) phone call between the first client and the second client.