Fraud Call Detection Using PLMN Location Verification

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Solution Overview

Problem

Existing systems fail to effectively detect and prevent fraud calls originating from spoofed caller IDs, particularly in international calls, allowing scammers to deceive recipients and perpetrate fraud.

Innovation Solution

A method and apparatus for automatically detecting fraud calls by identifying the origin of a call request through a local Public Land Mobile Network (PLMN) database, utilizing the CAMEL protocol's AnyTimeInterrogation (ATI) query to verify the Visitor Location Register (VLR) of the caller device, and determining the authenticity of the call based on the VLR's location relative to the local PLMN.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If caller ID spoofing is allowed in international calls, then call connectivity is maintained, but fraud detection capability is lost

Engineering Contradiction:
Improvefraud detection capabilityVSAvoidcall verification system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system performs preliminary verification of the caller's location against the called party's subscription location before allowing the call to proceed. By checking whether the caller is physically located in the country where the called party has a subscription, the system prevents fraud calls from being connected in the first place, thereby improving fraud detection capability without requiring complex real-time monitoring systems.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system introduces an intermediary verification mechanism that acts as a mediator between the calling party and the called party. This intermediary checks the geographic consistency between the caller's current location and the called party's subscription location, serving as a trust bridge that prevents spoofed calls while maintaining legitimate call connectivity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If location verification is performed for every incoming call, then fraud detection accuracy is improved, but call processing time increases

Engineering Contradiction:
Improvefraud detection accuracyVSAvoidcall processing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system applies partial verification by only checking location information when the caller's number is associated with a local PLMN but the call originates from a foreign network. This selective approach avoids unnecessary verification time for calls that are clearly legitimate or clearly fraudulent, while focusing computational resources only on the ambiguous cases that require location checking, thus improving accuracy without proportionally increasing processing time.

Inventive Principle:
Principle #16Partial or excessive action

3Reliability

If caller location is always verified, then call security is improved, but network scalability is reduced

Engineering Contradiction:
Improvecall securityVSAvoidnetwork scalability
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The system implements location verification selectively based on the specific characteristics of each call. Instead of applying uniform verification to all calls, it applies location checking only when necessary - specifically when the caller's number suggests local association but the call originates from abroad. This differentiated approach maintains high security for potentially fraudulent calls while avoiding the scalability penalties of universal verification.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4490903B1Automated fraud call detection
Publication Date: 2025.11.12 ELISA OYJ
  • EP4490903B1 patent drawingFigure 1
  • EP4490903B1 patent drawingFigure 2~3

AI summary

A computer-implemented method for automatically detecting a fraud call. A call request is received from a caller device to initiate a voice call with a called device at a local Public Land Mobile Network (PLMN). The call request is identified originating from a foreign Public Land Mobile Network (PLMN). In response to detecting that a caller ID of the caller device is associated to a local Public Land Mobile Network (PLMN), current location information is requested from a database of the local Public Land Mobile Network (PLMN). If the location information indicates the caller device is attached to the foreign Public Land Mobile Network (PLMN), determining the call request as authentic; and if the location information indicates the caller device is attached to the local Public Land Mobile Network (PLMN), determining the call request as fraud.