EPSFB Call Setup via Early UE VoNR Capability Detection

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Solution Overview

Problem

Existing 5G networks experience delays and call drops during voice call setup due to UEs lacking VoNR capability, requiring lengthy standardized call flows that inefficiently utilize network resources.

Innovation Solution

A 5G telecommunications system employs a server to determine UE capabilities and initiate EPSFB by generating alternative service messages, reducing the number of message exchanges and avoiding conflicts in the call setup process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If standardized call flow is used for EPSFB, then compatibility with legacy systems is maintained, but call setup time increases and call drops occur

Engineering Contradiction:

Improvecall setup success rateVSAvoidcall setup time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The network side determines UE VoNR capability in advance before initiating the standardized call flow, and proactively sends alternative service messages to guide UEs without VoNR capability to fallback procedures. This preliminary capability assessment prevents unnecessary execution of lengthy standardized call flows, reducing call setup time and avoiding call drops.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary mechanism where the network side acts as a mediator between UEs and the call setup process. By sending alternative service messages, the network intermediary guides UEs with insufficient capabilities to appropriate fallback procedures, resolving the contradiction between maintaining compatibility and reducing setup time.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If standardized call flow messages are exchanged, then protocol compatibility is ensured, but network resources are inefficiently utilized

Engineering Contradiction:

Improveprotocol compatibilityVSAvoidnetwork resource utilization efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent extracts the capability determination step from the standardized call flow sequence. By separately determining UE VoNR capability before initiating the call flow, the system avoids executing unnecessary standardized message exchanges for UEs without VoNR capability, thereby improving network resource utilization while maintaining protocol compatibility through selective application of call flows.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of always executing the complete standardized call flow, the system applies partial action by sending alternative service messages only to UEs that require fallback. This selective approach reduces unnecessary message exchanges and optimizes network resource usage while maintaining full protocol compatibility for UEs that do support VoNR.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS12376172B2Call setup for evolved packet system fallback

Publication Date: 2025.07.29 T MOBILE US INC

AI summary

Techniques for setting up a communication session associated with Evolved Packet System Fallback (EPSFB) are described herein. A fifth generation telecommunications network can implement a server to determine that a user equipment (UE) is incapable of establishing a Voice over New Radio (VoNR) call due to a chipset or other technology used by the UE. The server can send a message (e.g., a SIP380 Alternative Service message) to the UE to cause the UE to begin fallback to another network without waiting for an instruction from a base station in a standardized call flow. The server can establish the communication session for the UE using fewer call flow steps than a number of steps used by a standardized call flow.