Call Forwarding Detection in VoIP Interception
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Solution Overview
Problem
In networks providing voice over packet services, maintaining a unique Communication Identity Number (CIN) becomes difficult due to multiple nodes involved in signaling, as conventional algorithms fail to maintain the same CIN during call forwarding, treating the forwarded call as a new session.
Innovation Solution
A method that intercepts initial and forwarded call messages, comparing key fields like 'Call_ID', 'SDP O', 'To', 'From', 'Request-Uri', and 'History-Info-Uri' to determine if the forwarded call is part of the same communication session, allowing the same CIN to be used for analysis by an agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional algorithms are used to correlate signaling messages from different nodes, then a unique CIN can be maintained for the same communication session, but call forwarding events cause the system to treat the forwarded call as a new session with a new CIN
Solution Approach 1:
The correlation algorithm dynamically adapts its matching criteria based on the type of signaling message and the presence of call forwarding indicators. The system transitions from static CIN-based correlation to a dynamic approach that adjusts correlation parameters according to message type (INVITE, ACK, BYE) and call forwarding detection, enabling consistent CIN maintenance through forwarding events while preserving reliability.
Solution Approach 2:
The system changes correlation parameters when call forwarding is detected. Specifically, it modifies the matching criteria from requiring exact CIN matches to using alternative correlation parameters such as comparing message types, directions, and temporal relationships. This parameter adaptation allows the system to maintain CIN consistency across forwarded calls while handling the versatility of different call scenarios.
2Ease of operation
If the system treats forwarded calls as new sessions with new CINs, then call forwarding events are handled independently, but intercepted information becomes fragmented and cannot be analyzed as a whole
Solution Approach 1:
The system introduces an intermediary correlation mechanism that acts as a mediator between forwarded calls and the original session. By detecting call forwarding events and using alternative correlation parameters (message type, direction, timing) to link forwarded calls to their parent sessions, the intermediary maintains information continuity while allowing independent handling of each call event, preventing information fragmentation.
Solution Approach 2:
The system adds another dimension to call correlation by introducing temporal and directional analysis alongside traditional CIN matching. It examines the sequence of messages (INVITE→ACK→BYE), their directions (incoming/outgoing), and timing relationships to correlate forwarded calls with original sessions. This multi-dimensional approach preserves call session continuity while maintaining ease of independent call handling.
3Productivity
If multiple CINs are assigned to forwarded calls, then each call event can be processed independently through existing algorithms, but the network operator cannot relate initial and redirected calls to maintain the same CIN
Solution Approach 1:
The system performs preliminary detection of call forwarding events by analyzing signaling messages for specific indicators (e.g., Call-Info headers, diversion uris) before final correlation is made. This preliminary action allows the system to prepare alternative correlation parameters in advance, enabling both efficient independent processing of call events and precise maintenance of CIN consistency across the complete call session lifecycle.
Data Source
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AI summary
A mechanism for maintaining the same communication identity number when intercepted calls are forwarded is embodied in various methods, devices and media- storing software.