Dual-SIM Circuit-Switched Emergency Call Fallback

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Solution Overview

Problem

Existing wireless communication systems face challenges in making emergency calls when a first subscriber identity module (SIM) fails, leading to disabling of radio access network capabilities and increased latency and power consumption during fallback attempts.

Innovation Solution

A method and apparatus for a user-equipment (UE) to attempt a circuit-switched emergency call via a first SIM, detect failure, and re-attempt the call via a second SIM, thereby avoiding disabling of radio access network capabilities and reducing latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE attempts a CS emergency call via the first SIM (DDS) and fails, then the system disables radio access network capabilities to force fallback, but this increases latency and disables network services

Engineering Contradiction:

Improveemergency call success rateVSAvoidcall setup latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent segments the emergency call attempt process into multiple independent paths: first attempting via the default data subscriber (DDS) SIM, and if that fails, attempting via the non-DDS SIM. This segmentation allows the system to avoid disabling radio access network capabilities entirely, instead routing calls through different subscriber modules to maintain network service availability while improving emergency call success rates.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the UE disables radio access network capabilities after CS emergency call failure, then the system forces fallback to alternative networks, but this increases power consumption and latency

Engineering Contradiction:

Improveemergency call fallback capabilityVSAvoidpower consumption during fallback

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent introduces the non-DDS SIM as an intermediary alternative path. Instead of completely disabling radio access network capabilities and forcing a full fallback process, the system uses the non-DDS SIM as an intermediate solution that can handle emergency calls when the DDS SIM fails, thereby reducing the energy consumption and latency associated with complete capability disabling and network re-registration.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If the UE uses a single SIM for all communications, then the system is simpler to manage, but emergency call reliability decreases when that single SIM fails

Engineering Contradiction:

ImproveSIM management complexityVSAvoidemergency call success rate

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies local quality by assigning different roles to different SIMs: the DDS SIM handles default data subscriber functions, while the non-DDS SIM is specifically configured to handle emergency calls. This differentiation allows each SIM to have optimized local functionality, improving overall emergency call reliability without requiring complex unified management of multiple SIMs.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12446112B2Method for improved emergency call

Publication Date: 2025.10.14 QUALCOMM INC

AI summary

Aspects of the present disclosure provide techniques for improving emergency calls by a user equipment (UE) in certain scenarios. The techniques generally include receiving a trigger for the UE to perform a circuit switched (CS) emergency call via a first subscriber identity module (SIM) that is serving as a default data subscriber (DDS), attempting the CS emergency call via the first SIM, detecting a failure to perform the CS emergency call via the first SIM, and re-attempting the CS emergency call via a second SIM, in response to the detection.