IMS Charging Mechanism for SIP Parallel Forking Accuracy
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Solution Overview
Problem
Conventional charging procedures in IMS systems fail to correctly handle SIP parallel forking, leading to incorrect charging and users being charged for unused services during multimedia communication sessions.
Innovation Solution
A method and apparatus that accurately determine which branch to charge in case of forking, ensuring users only pay for services actually used, by using a connection terminating message with a Reason Header and trust parameter to differentiate between used and unused branches, applicable to both online and offline charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional charging procedures are used in IMS systems, then charging can be performed for multimedia communication sessions, but users are incorrectly charged for unused services and signaling during SIP parallel forking
Solution Approach 1:
The patent segments the charging process by introducing a forking indicator that divides the charging logic into distinct paths: one for successful forking branches and another for unsuccessful ones. This segmentation allows the charging system to accurately identify which branch resulted in a successful connection and charge only that branch, preventing unjustified charges for unused services.
Solution Approach 2:
The patent introduces a forking indicator as an intermediary element that carries information about forking status between network elements. This indicator acts as a mediator that enables the charging system to distinguish between successful and unsuccessful forking branches without requiring complex modifications to the existing charging architecture.
2Adaptability or versatility
If SIP parallel forking is implemented to improve service availability, then users can reach multiple destinations simultaneously, but charging procedures cannot correctly identify which branch to charge
Solution Approach 1:
The patent implements a feedback mechanism where the forking indicator provides information back to the charging system about the outcome of each forking branch. This feedback loop enables the charging system to identify which branch was successful and should be charged, resolving the information loss problem inherent in parallel forking scenarios.
Solution Approach 2:
The forking indicator serves as an intermediary that preserves and transmits forking branch identification information throughout the charging process. This intermediary element ensures that information about which branch succeeded is not lost, enabling accurate charging despite the parallel nature of forking.
3Ease of operation
If charging procedures handle all forking branches equally, then charging can be simplified, but users are charged for signaling and unused branches
Solution Approach 1:
The patent segments the charging procedure into distinct handling paths based on forking outcome. By introducing the forking indicator, the system maintains operational simplicity while enabling differentiation between charged and non-charged branches, avoiding unjustified charges for unused services.
Solution Approach 2:
The forking indicator enables the charging system to automatically identify and charge only the successful branch without requiring complex manual intervention or additional network elements. The system serves itself by using the indicator to make autonomous charging decisions.
Data Source
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AI summary
A network node, such as a network control node like a CSCF or an application server, executing forking forward only the first successful response message arriving from a forking branch, which enables the charging function in the forking node and in nodes in the backward direction from this point to apply charges only for the "winning" branch. By including a special Reason header sent in a BYE request of "unused" successfully contacted branches, charging function in nodes in the forward direction from the forking point are allowed to suppress charges for such unused branches. This is applicable both for online and offline charging methods as defined, for example, by 3GPP.