GSM Silent Call Prolongation Using Unrealizable SETUP Messages

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Solution Overview

Problem

Newer mobile stations terminate GSM silent calls prematurely, preventing effective localization due to early abort of the call, which is critical for security applications.

Innovation Solution

A method involving a BTS or BSC to establish a mobile terminated call without an assignment command, followed by sending unrealizable SETUP messages to prolong the silent call, maintaining the communication link through repeated unrealizable messages until localization is complete.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a GSM silent call is established for localization purposes, then the mobile station can be located, but the call is terminated too early by newer mobile stations

Engineering Contradiction:

Improvelocalization completionVSAvoidcall duration

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The network sends unrealizable SETUP messages before the mobile station can terminate the call, proactively extending the call duration. These messages are sent in advance to ensure the call remains active long enough for localization to complete, preventing premature termination by newer mobile stations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Unrealizable SETUP messages act as intermediaries between the network and mobile station. These messages cannot be properly processed by the mobile station (as they contain invalid or unsupported parameters), causing the mobile station to release them and thereby extending the call duration without affecting normal call functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Duration of action of moving object

If unrealizable SETUP messages are sent repeatedly to prolong the call, then the call duration is extended, but the network complexity increases

Engineering Contradiction:

Improvecall durationVSAvoidnetwork procedure complexity

Core Design Contradiction:

Duration of action of moving objectVSDevice complexity

Solution Approach 1:

The unrealizable SETUP messages are simple, disposable message structures that can be easily generated and sent by the network. Each message contains minimal invalid or unsupported parameters, making them computationally inexpensive to create and process, thereby extending call duration without significantly increasing network complexity.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS12568535B2Method and apparatus for GSM silent call prolongation

Publication Date: 2026.03.03 ROHDE & SCHWARZ GMBH & CO KG

AI summary

A method for GSM silent call prolongation comprises a first step of activating a mobile station by establishing a mobile terminated call, MTC, communication link to the mobile station. The establishing of the MTC communication link is performed without sending an assignment command message to the mobile station. The method comprises a second step of sending a first unrealizable SETUP message to establish the silent call. The method comprises a third step of sending at least one more unrealizable SETUP message to prolong the silent call.