SIP Call Context Conveyance via REFER and INVITE Messages

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Solution Overview

Problem

In communication systems using Session Initiation Protocol (SIP), there is a lack of context delivery when calls are redirected, particularly in contact centers, leading to unclear reasons for incoming calls and challenges in maintaining call context during topology changes.

Innovation Solution

The implementation of a communication system that conveys transitive and relative call context through SIP messages, such as REFER and INVITE messages, to ensure continuity and provide necessary information during call topology changes and participant additions, using specific headers and MIME attachments to manage context information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If call redirection is implemented using SIP, then call mobility and flexibility are improved, but call context information is lost during transfer

Engineering Contradiction:

Improvecall mobilityVSAvoidcall context

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent applies preliminary action by embedding context information (such as transfer reason, original caller details, and call purpose) into the REFER request message before the call transfer occurs. This ensures that the receiving party has all necessary context information in advance, eliminating the need for verbal context relay and preventing information loss during call mobility operations.

Inventive Principle:

Principle #10Preliminary action

2Loss of information

If attended transfer is used to relay call context, then call context information is preserved, but call handling time and complexity increase

Engineering Contradiction:

Improvecall contextVSAvoidcall handling time

Core Design Contradiction:

Loss of informationVSLoss of time

Solution Approach 1:

The system applies self-service by automatically extracting, formatting, and transmitting call context information through SIP REFER requests without requiring human intervention. The call management system autonomously handles context preservation by embedding relevant data in the transfer message, eliminating the need for agents to verbally relay context and thereby reducing call handling time while maintaining complete information integrity.

Inventive Principle:

Principle #25Self-service

3Loss of information

If multiple context parameters are transmitted in SIP messages, then call context completeness is improved, but message complexity and processing overhead increase

Engineering Contradiction:

Improvecall context completenessVSAvoidmessage processing complexity

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing call context information into distinct, standardized parameters within the SIP REFER request message body. Each context element (transfer reason, original caller, call purpose, etc.) is structured as a separate data field, allowing receiving systems to selectively process only the parameters relevant to their function. This structured segmentation reduces processing complexity while maintaining complete context information transmission.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10200418B2Call context conveyance

Publication Date: 2019.02.05 AVAYA INC

AI summary

A communication system, method, and components are described. Specifically, a communication system having the ability to carry a transitive context and communicate the transitive context to new participant user agents for continuity through all related call dialogs is disclosed. The transitive context communication is possible through the use of a newly created SIP dialog using a REFER message and/or an INVITE message for all call flows and topology change operations.