Advice of Charge Application Server for SIP Session Authorization
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Solution Overview
Problem
Existing systems face difficulties in implementing the Advice of Charge (AoC) supplementary service in SIP networks, particularly in correlating messages across different dialogs and ensuring user consent before session setup, which complicates charging information provision and end-to-end security.
Innovation Solution
The system employs an AoC Application Server that acts as both a SIP proxy and user agent, providing charging information through MESSAGE requests and using a Digest challenge to obtain user authorization before proceeding with session setup, allowing users to confirm charges before initiating or continuing a session.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the S-CSCF holds processing of INVITE request until charge information is received, then accurate charging information can be provided, but the system complexity increases and S-CSCF logic becomes overly complicated
Solution Approach 1:
The patent introduces an Application Server (AS) as an intermediary component that专门 handles charge information provision. The AS receives the INVITE request, determines charging information, and provides it to the user equipment without requiring the S-CSCF to hold or complexly process the request. This mediator approach resolves the contradiction by centralizing the complex charging logic in a dedicated AS while keeping the S-CSCF processing simple and stateless.
Solution Approach 2:
The patent segments the charging function from the core SIP routing function by implementing it as a separate Application Server. The S-CSCF only performs basic SIP routing, while the AS handles charge information determination and provision. This functional segmentation resolves the contradiction by preventing the S-CSCF from becoming overly complex while ensuring accurate charging information is still provided through the specialized AS component.
2Reliability
If the AoC AS acts as a Back-to-Back User Agent, then charge information can be provided, but end-to-end security is prevented and additional correlation logic is required
Solution Approach 1:
The patent uses the Application Server as a mediator that processes charge information without acting as a Back-to-Back User Agent. The AS receives the INVITE, determines charges, and provides information to the user equipment, then allows the original SIP dialog to continue normally. This approach maintains end-to-end security by avoiding the B2BUA pattern while still reliably delivering charge information through the intermediary AS.
3Reliability
If charge information is provided in provisional responses, then the user can see charges during setup, but correlating messages across different dialogs becomes difficult
Solution Approach 1:
The Application Server acts as a mediator that receives the complete INVITE request, determines charging information based on the full session parameters, and provides the charge information to the user equipment through a separate mechanism. This approach eliminates the need to correlate messages across different dialogs because the AS processes all correlation logic internally before providing charge information, thus resolving the contradiction between timely charge disclosure and message correlation complexity.
Data Source
AI summary
The invention provides a system, method, and network elements for providing a service, preferably an advice of charge, AoC, service requested by a user equipment at a session set-up or during a session. An application server provides information for the requested service to the user equipment. In an embodiment, authorization information and the information for the requested service may be sent to the user equipment. Depending on an input by the user or other type of confirmation such as expiration of a timer, the user equipment may initiate continuation of the session, for example by generating an authorization response based on the received authorization information, and sending the generated authorization response to the application server for verification.