VoIP Call Loop Detection via Provisional State Monitoring
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Solution Overview
Problem
VoIP systems lack effective mechanisms to prevent call loops when multiple carriers are involved, leading to potential network overloads and billing issues due to the absence of a permanent header to uniquely identify calls and the rapid propagation of loops.
Innovation Solution
A method and system for detecting call loops by checking for duplicate calls with the same destination and origination numbers, determining the number of calls in a provisional state within a specified time interval, and terminating the call if the threshold is exceeded, with the option to provide an error code.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple carriers are involved in handling the same phone call with high call speeds, then call processing capacity is improved, but call loop propagation increases and network stability deteriorates
Solution Approach 1:
The system performs preliminary detection of call loops by monitoring the number of calls in provisional state with the same destination number before calls are fully established. When the threshold is exceeded, the system proactively terminates the call, preventing loop propagation before it can cause network overload or billing issues.
2Reliability
If call loop detection is implemented by monitoring calls in provisional state, then call loop prevention is improved, but system complexity increases
Solution Approach 1:
The system uses the existing Call-ID header from SIP messages as a copy mechanism to identify and track calls across multiple carriers. By reusing this existing identifier rather than creating a new tracking system, the solution achieves effective call loop detection while minimizing additional system complexity.
3Adaptability or versatility
If the Call-ID header is replaced by intermediate carriers, then carrier flexibility is improved, but call identification capability deteriorates
Solution Approach 1:
The system implements feedback by monitoring the number of calls in provisional state with the same destination number and comparing it against a threshold. This feedback mechanism allows the system to detect potential call loops even when Call-ID is replaced, and take corrective action by terminating suspicious calls before they can cause network issues.
Data Source
AI summary
A method, system, and computer program product for providing call loop detection and prevention for VoIP SIP based wholesale traffic termination when multiple carriers are involved in handling the same phone call is provided. A method of detecting a call loop includes receiving an originated call, determining whether an origination number of the originated call is a valid phone number, when the origination phone number is invalid, determining a number of calls in a Provisional State with an invalid origination number and the same destination number that were started during a time interval, when the origination phone number is valid, determining a number of calls with the same origination number and the same destination number that were started, but not answered, during the time interval, and when the number of calls per time interval exceeds a threshold for the number of calls, determining that a call loop has been detected.