IMS Session Rerouting for VoLTE Termination Reliability

Solution Overview

Problem

Integrated Internet Protocol (IP) Multimedia Subsystem (IMS) infrastructures face challenges in handling session invitations between users with different IMS capabilities and authorizations, leading to failed VoLTE/VoWiFi session terminations due to insufficient capabilities or authorizations of the terminating subscriber.

Innovation Solution

The IMS infrastructure determines the capabilities and authorizations of subscribers for RCS-messaging-only and VoLTE/VoWiFi services, rerouting VoLTE or VoWiFi session invitations to a Circuit Switched (CS) network using a Breakout Gateway (BG) and Media Gateway Control Function (MGCF) based on determined capabilities and authorizations, ensuring fail-safe session termination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the IMS infrastructure hosts multiple IMS services (RCS-messaging-only and VoLTE/VoWiFi) on the same platform, then service integration and resource utilization are improved, but session termination reliability deteriorates when subscribers lack necessary capabilities or authorizations

Engineering Contradiction:

Improveservice integrationVSAvoidsession termination reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system performs preliminary capability and authorization checks for the terminating subscriber before establishing a VoLTE/VoWiFi session. The S-CSCF determines whether the subscriber has the necessary capabilities and authorizations, and if not, reroutes the session invitation to the CS network in advance, preventing termination failures.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The S-CSCF acts as an intermediary that mediates between the VoLTE/VoWiFi session invitation and the terminating subscriber. It determines subscriber capabilities and authorizations, and based on this determination, selects the appropriate network path (IMS or CS) for session termination, ensuring reliable connectivity regardless of subscriber capabilities.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If the system attempts to terminate VoLTE/VoWiFi sessions directly to subscribers without capability verification, then session establishment speed is improved, but session termination success rate deteriorates due to insufficient subscriber capabilities

Engineering Contradiction:

Improvesession establishment speedVSAvoidsession termination success rate

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The system performs preliminary capability and authorization checks for the terminating subscriber before establishing a VoLTE/VoWiFi session. The S-CSCF determines whether the subscriber has the necessary capabilities and authorizations, and if not, reroutes the session invitation to the CS network in advance, preventing termination failures.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically changes the network path parameter based on subscriber capability parameters. When the terminating subscriber lacks VoLTE/VoWiFi capabilities or authorizations, the S-CSCF changes the session route from the IMS network to the CS network, ensuring successful termination while maintaining fast session establishment.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the IMS infrastructure reroutes sessions to CS network for subscribers without VoLTE/VoWiFi capabilities, then session termination reliability is improved, but network complexity increases due to multiple routing paths

Engineering Contradiction:

Improvesession termination reliabilityVSAvoidnetwork routing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The S-CSCF acts as an intermediary that mediates between the VoLTE/VoWiFi session invitation and the terminating subscriber. It determines subscriber capabilities and authorizations, and based on this determination, selects the appropriate network path (IMS or CS) for session termination, ensuring reliable connectivity regardless of subscriber capabilities.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically changes the network path parameter based on subscriber capability parameters. When the terminating subscriber lacks VoLTE/VoWiFi capabilities or authorizations, the S-CSCF changes the session route from the IMS network to the CS network, ensuring successful termination while maintaining fast session establishment.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3054644B1Voice session termination for messaging clients in IMS

Publication Date: 2018.06.06 VODAFONE GMBH

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AI summary

An IMS structure is described that hosts an IMS service based on a Rich Communication Suite (RCS) protocol for messaging only and IMS service based on VoLTE or Voice over WiFi. The IMS comprises functionality for rerouting a VoLTE or VoWiFi session invitation to a subscriber via a circuit switched network based on determined capabilities and authorizations of the invited subscriber.