UE Emergency Number Provisioning for Faster Domain Selection

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Solution Overview

Problem

Existing systems face inefficiencies and delays in handling emergency calls when a user equipment (UE) is redirected between different network domains, leading to time-consuming retries and potential termination of calls, especially in scenarios where traditional voice services are unavailable.

Innovation Solution

The UE is equipped with a method to transmit a request message as part of a Network Access Stratum (NAS) procedure, receive a response message containing a list of emergency numbers, and determine the appropriate domain for call setup, either performing emergency or basic call setup procedures based on the selected domain, thereby optimizing call handling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the UE is redirected between different network domains during emergency call attempts, then the call can be routed to available services, but the call setup time increases and may cause user termination

Engineering Contradiction:

Improvecall routing flexibilityVSAvoidcall setup time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The system performs preliminary actions by providing the UE with emergency number information and domain selection capabilities before the emergency call attempt. The network delivers emergency number lists and domain preferences to the UE in advance, so when an emergency call is needed, the UE can immediately select the appropriate domain without redirection delays.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the UE performs multiple retries after redirection, then the emergency call may eventually connect, but the complexity of call handling increases and user experience deteriorates

Engineering Contradiction:

Improvecall connection reliabilityVSAvoidcall handling complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The network provides the UE with emergency number information and domain selection preferences before the emergency call attempt. This preliminary provision of information allows the UE to directly select the correct domain for emergency calls without needing to perform multiple retries or complex redirection procedures.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If traditional voice services are unavailable, then the system must use alternative routing methods, but the call setup procedure becomes more complex and time-consuming

Engineering Contradiction:

Improveservice availabilityVSAvoidcall setup time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The network proactively provides the UE with emergency number information and domain selection preferences before traditional voice services become unavailable. This allows the UE to immediately switch to alternative routing methods without experiencing the delays and complexity of ad-hoc service discovery and selection.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP4184890B1Methods and systems for provisioning emergency numbers

Publication Date: 2026.04.22 BLACKBERRY LTD

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AI summary

There is provided a method and device for provisioning emergency number information on a user equipment. When a dialed number matches an emergency number from the provisioned emergency number information, the user equipment selects either the circuit switched domain or the packet switched domain and executes a call setup procedure for that domain.