SIP User Release via Timeout-Based Reassignment

Solution Overview

Problem

Existing methods for releasing a SIP user from a Serving Call Session Control Function (S-CSCF) in an IMS network often result in service disruptions, as they rely on users subscribing to registration event notifications, which may not always be subscribed to, leading to overloading or lack of functionality.

Innovation Solution

The system waits for the SIP user to refresh its registration and responds with a 504 server timeout, redirecting the user to a different S-CSCF without immediate deregistration, allowing for graceful shutdown and rebalancing of users across different serving functions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the system relies on users subscribing to registration event notifications for releasing SIP users, then the user release mechanism can be implemented, but it leads to service disruptions and overloading when subscriptions are not present

Engineering Contradiction:

Improveservice continuityVSAvoidsubscription management complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the dependency on registration event notification subscriptions from the user release mechanism. Instead of requiring users to subscribe to notifications for release, the system uses a timeout-based mechanism where the S-CSCF automatically releases users after a predetermined period without receiving refresh requests, thereby eliminating the complexity of subscription management while maintaining service continuity

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system performs preliminary actions by establishing a timeout mechanism in advance. The S-CSCF sets a predetermined timeout period and monitors for refresh requests during this period. If no refresh is received before the timeout expires, the user is automatically released. This preliminary timeout setup prevents service disruptions by ensuring orderly user release without requiring complex subscription management

Inventive Principle:

Principle #10Preliminary action

2Productivity

If the system performs immediate deregistration of SIP users, then resource allocation is optimized, but service outages occur during the transition

Engineering Contradiction:

Improveresource allocation efficiencyVSAvoidservice availability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system performs preliminary actions by establishing a timeout mechanism in advance. The S-CSCF sets a predetermined timeout period and monitors for refresh requests during this period. If no refresh is received before the timeout expires, the user is automatically released. This preliminary timeout setup prevents service disruptions by ensuring orderly user release without requiring complex subscription management

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies beforehand cushioning by implementing a grace period (timeout mechanism) before actual user release. During this cushioning period, the system continues to accept refresh requests from users, providing a buffer that prevents abrupt service outages. This cushioning approach allows for smooth transition and resource reallocation while maintaining service availability

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If the system waits for users to refresh registration before releasing, then service continuity is maintained, but resource rebalancing is delayed

Engineering Contradiction:

Improveservice continuityVSAvoidrebalancing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary actions by establishing a timeout mechanism in advance. The S-CSCF sets a predetermined timeout period and monitors for refresh requests during this period. If no refresh is received before the timeout expires, the user is automatically released. This preliminary timeout setup prevents service disruptions by ensuring orderly user release without requiring complex subscription management

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies periodic action through the timeout mechanism that periodically checks for user refresh requests. The S-CSCF monitors the timeout period systematically, and upon expiration without refresh, triggers the release process. This periodic monitoring enables timely resource rebalancing while maintaining service continuity during the monitoring period

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS9584551B2SIP user release

Publication Date: 2017.02.28 ORACLE INT CORP

AI summary

A system that releases a Session Initiation Protocol (“SIP”) user from a serving function on an Internet Protocol Multimedia Subsystem (“IMS”) network receives a REGISTER refresh from a registered user equipment (“UE”). In response to the REGISTER refresh, the system sends a server assignment request to a home subscriber server (“HSS”) that clears the name of the Serving Call Session Control Function (“S-CSCF”) assigned for the registered user. The system then sends a gateway timeout or server timeout that would trigger the UE to send an initial REGISTER request.