SIP Message Handling via P-Served-User-Identity Header
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Solution Overview
Problem
In the IP Multimedia Subsystem (IMS), existing technologies face challenges in handling call forwarding scenarios, where the Serving Call/Session Control Function (S-CSCF) struggles to authenticate and apply Initial Filter Criteria (IFCs) correctly, especially when messages are forwarded between Application Servers, due to inconsistencies in the P-Asserted Identity and R-URI, which can lead to incorrect handling of messages.
Innovation Solution
Introducing a new header, 'P-Served-User-Identity', at the S-CSCF before forwarding messages to an Application Server, explicitly identifying the user served by the S-CSCF, allowing the Application Server to handle messages based on defined criteria, thereby enabling correct authentication and re-routing without altering the P-Asserted Identity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the S-CSCF uses existing P-Asserted Identity and R-URI for message handling in call forwarding scenarios, then the message routing can proceed with standard protocols, but the authentication and Initial Filter Criteria application become incorrect due to identity inconsistencies
Solution Approach 1:
The patent segments the user identity information into two distinct components: the original P-Asserted Identity (preserving the caller's identity) and a new P-Served-User-Identity header (identifying the user being served). This segmentation allows the system to maintain both the caller's identity for routing purposes and the served user's identity for authentication and IFC application, resolving the identity inconsistency problem without complicating the overall message handling flow.
Solution Approach 2:
The patent introduces the P-Served-User-Identity header as an intermediary element that mediates between the original P-Asserted Identity and the authentication/IFC application processes. This intermediary carries the served user's identity information through the message exchange, enabling correct authentication and IFC application while preserving the original routing identity, thus improving reliability without requiring fundamental changes to the message handling architecture.
2Reliability
If the S-CSCF modifies the P-Asserted Identity to resolve identity inconsistencies, then authentication accuracy improves, but the original caller identity information is lost
Solution Approach 1:
Instead of modifying the P-Asserted Identity, the patent segments identity information by introducing a separate P-Served-User-Identity header. This preserves the original P-Asserted Identity (containing caller information) while adding a new header that carries the served user's identity. This segmentation approach simultaneously improves authentication accuracy and prevents loss of caller identity information.
Solution Approach 2:
The patent creates a copy of the identity information mechanism by introducing the P-Served-User-Identity header as a duplicate carrier for user identity, but specifically for the served user rather than the caller. This copying approach allows the system to have both the original caller identity (in P-Asserted Identity) and the served user identity (in the new header), eliminating the need to modify or lose any identity information.
3Measurement precision
If the S-CSCF introduces a new header to explicitly identify the served user, then authentication and IFC application accuracy improve, but the message structure complexity increases
Solution Approach 1:
The P-Served-User-Identity header acts as a simple intermediary element that carries served user identity information without requiring complex message structure changes. It follows the existing SIP header format conventions, integrating seamlessly into the current message structure. This intermediary approach improves identity identification accuracy while minimizing increases in message structure complexity.
Solution Approach 2:
The new P-Served-User-Identity header is designed to be universally compatible with existing SIP message handling mechanisms. It can be applied across different message types and scenarios (call forwarding, authentication, IFC application) without requiring scenario-specific modifications. This universality improves measurement precision for identity identification while keeping the message structure enhancement minimal and reusable across multiple functions.
Data Source
AI summary
A method of handling a Session Initiation Protocol (SIP) communication at a SIP application server within an IP Multimedia Subsystem, the method including handling a message received from a Serving Call/State Control Function node based upon a header of the message containing the URI of the served user. The SIP message is handled according to one of an originating case based upon a P-Asserted Identity contained in the SIP message or a terminating case using a Request-Uniform Resource Identifier (R-URI) of the SIP message, the appropriate case being identified in said header.