IMS Network Transfer Detection via SIP Call-Info Header
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing IP Multimedia Subsystem (IMS) networks lack a mechanism to detect and manage the transfer of communication sessions between endpoints, which hinders lawful interception requirements, as there is no way for nodes to determine if a communication has been transferred to another user.
Innovation Solution
The introduction of an explicit communication transfer indicator (ECT) within SIP messages, such as the Call-Info header, allows IMS nodes to detect transfers and inform Lawful Intercept nodes, enabling them to take necessary actions, including stopping lawful interception when applicable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an explicit communication transfer indicator is introduced in SIP messages, then the ability to detect and manage communication transfers is improved, but the message complexity and processing overhead increase
Solution Approach 1:
The explicit communication transfer indicator is nested within existing SIP message structures, specifically utilizing the Call-Info header field. This allows the transfer indication to be embedded within the established SIP protocol framework without requiring a completely new message format, thereby improving transfer detection capability while minimizing increases in overall message complexity.
Solution Approach 2:
The Call-Info header field serves as an intermediary structure that carries the explicit communication transfer indicator. By using this existing header field as a mediator, the patent enables transfer detection functionality without directly modifying core SIP message structures, thus balancing reliability improvement with controlled complexity increase.
2Reliability
If nodes in the IMS network are equipped to detect transfers, then lawful interception compliance is improved, but the network node complexity and processing requirements increase
Solution Approach 1:
The detection and processing of transfer indicators is extracted as a distinct function within IMS nodes. Nodes examine the Call-Info header field for specific indicators and trigger appropriate lawful interception procedures only when transfer indications are present. This extraction approach enables compliance improvement while avoiding unnecessary processing complexity in nodes that do not encounter transfer scenarios.
Solution Approach 2:
The explicit communication transfer indicator provides feedback to IMS nodes about transfer events. This feedback mechanism enables nodes to automatically adjust their lawful interception behavior based on the transfer status, improving compliance through automated response while reducing the need for complex manual monitoring and decision-making processes.
3Measurement precision
If transfer detection mechanisms are implemented, then the precision of communication tracking is improved, but the processing time and signaling overhead increase
Solution Approach 1:
The explicit communication transfer indicator is embedded in the Call-Info header field during the call setup and transfer phases. By having this indicator prepared and available in advance within the SIP message structure, nodes can detect transfers immediately when the message is received, improving detection precision without requiring additional processing time for indicator generation or message waiting.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method and apparatus for indicating to a node in an IMS network a transfer between two endpoints. A node in a first network determines that a communication session is to be transferred from a first endpoint to a second endpoint. The node includes an indication of at least one of the endpoints, and an explicit communication transfer indicator, in a message. The message is then sent towards the node in the IMS network. This allows the node in the IMS network to determine that a transfer has taken place and, if necessary, take further action.