SIP Session Manager Spiral Call Identification
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Solution Overview
Problem
SIP call stateful proxies face challenges in uniquely identifying session contexts for spiral calls, leading to potential overwriting of state information and communications failures, as the same session context identifier is used for both original and forwarded calls.
Innovation Solution
A method for identifying session contexts involves generating unique identifiers for new sessions, inserting them into the Record-Route header, and using these identifiers to create and access session context database records, ensuring distinct identification of original and spiral calls by embedding the unique identifiers in SIP request messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same session context identifier is used for original and spiral calls, then the proxy can simplify identifier generation and storage, but the proxy may mistakenly overwrite state information for the original call when receiving the spiral call
Solution Approach 1:
The patent segments the session context identifier into two parts: the original Call-Id (which remains the same for both original and spiral calls) and a new Spiral-Id (which is unique to each spiral call). This segmentation allows the system to maintain simplicity in identifier generation while preventing overwriting of state information by using the Spiral-Id to distinguish between different spiral calls that may have the same Call-Id.
Solution Approach 2:
The patent introduces the Spiral-Id as an intermediary element between the Call-Id and the full session context identifier. The Spiral-Id acts as a mediator that carries additional information about the spiral call path and distinguishes different spiral calls. This intermediary allows the proxy to accurately identify and separate state information for different spiral calls without complicating the overall identifier structure.
2Adaptability or versatility
If the proxy uses Call-Id and tags to identify session contexts, then the proxy can maintain compatibility with standard SIP protocols, but the proxy cannot distinguish between original calls and spiral calls with the same Call-Id
Solution Approach 1:
The patent adds another dimension to the session context identification by introducing the Spiral-Id as an additional identifier layer. Instead of relying solely on the Call-Id and tags (which are sufficient for standard SIP compatibility), the system augments the identification with the Spiral-Id that captures the spiral call path information. This dimensional expansion allows the proxy to distinguish between original and spiral calls while maintaining backward compatibility with standard SIP protocols.
3Ease of operation
If the proxy forwards the spiral call to the same destination as the original call, then the proxy can simplify routing logic, but the proxy may cause communication failures by overwriting state information
Solution Approach 1:
The patent performs preliminary action by generating and attaching the Spiral-Id to the spiral call request before routing. The Spiral-Id is created when the proxy detects a spiral call (when the Request-URI differs from the original call) and is attached to the request message. This preliminary identification allows the proxy to correctly route the spiral call to the appropriate destination while maintaining separate state information, preventing communication failures that would occur with overwriting.
Data Source
AI summary
A method for identifying session contexts for handling spiral calls includes, at a SIP session manager, receiving, from a first node, a first SIP request message. The method further includes determining that the first SIP request message is a request for establishing a new session or subscription. The method further includes, in response to determining that the first SIP request message is a request for establishing a new session or subscription, generating a first unique identifier. The method further includes using the first unique identifier as or to generate a first session context identifier. The method further includes creating a first session context database record for the first session or subscription. The method further include inserting the first unique identifier in a Record-Route header. The method further includes adding the Record-Route header to a first outbound SIP request message and routing the first outbound SIP request message.