VoIP Switch Neighbor Spoofing Detection via LRN Verification

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Solution Overview

Problem

Robocalls using neighbor spoofing techniques are difficult to identify and mitigate, as scammers constantly vary calling party numbers within local areas, making it challenging for telecommunications carriers and users to determine the origin of these calls, and existing technologies like SHAKEN/STIR are limited in detecting spoofed calls across non-S/S enabled switches.

Innovation Solution

A switch is configured to authenticate calling party numbers by determining the local routing number associated with the call and checking if it belongs to the same switch or an S/S enabled switch, allowing for processing of spoofed calls by playing intercept announcements, routing to voicemail, or rejecting calls, thereby identifying and mitigating neighbor spoofed calls.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If carriers block calls using unassigned numbers, then robocalls from unassigned numbers are reduced, but scammers adapt by spoofing assigned subscriber numbers instead

Engineering Contradiction:

Improverobocalls from unassigned numbersVSAvoidscammer adaptation to spoof assigned numbers

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The system performs preliminary authentication of the calling party number by verifying it against the switch's local routing number before the call is completed. This preliminary check identifies spoofed calls in advance, allowing the system to take preventive action (blocking, intercept announcements) before the called party is affected, thereby stopping both unassigned number robocalls and assigned number spoofing adaptations.

Inventive Principle:

Principle #10Preliminary action

2Object-affected harmful factors

If carriers disconnect spoofed numbers from service, then spoofing using that number stops, but the legitimate subscriber loses access to their number

Engineering Contradiction:

Improvespoofing activityVSAvoidsubscriber access to their number

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The system introduces an intermediary authentication mechanism that verifies whether a calling party number actually originated from the switch that claims it. Instead of immediately disconnecting the number, the system acts as an intermediary checker that can identify spoofing attempts while allowing legitimate calls to proceed normally. This intermediary verification layer protects both the subscriber's access and the network from spoofing.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If carriers use analytics to detect spoofed numbers, then detection accuracy improves, but processing complexity and time increase

Engineering Contradiction:

Improvedetection accuracy of spoofed callsVSAvoidanalytics processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system extracts and verifies the critical authentication element (the relationship between calling party number and local routing number) from the complex analytics processing. By focusing on this single key verification - checking if the calling party number matches the switch's own routing number - the system achieves high detection accuracy without the need for complex multi-factor analytics, thereby reducing processing complexity while maintaining precision.

Inventive Principle:

Principle #2Taking out (Extraction)

4Reliability

If SHAKEN/STIR is deployed on all switches, then spoofed call detection is comprehensive, but implementation cost and complexity increase significantly

Engineering Contradiction:

Improvecomprehensive spoofed call detectionVSAvoidimplementation complexity across network

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system implements a self-service authentication mechanism where each switch verifies incoming calls by checking if the calling party number corresponds to its own local routing number. This self-verification approach eliminates the need for complex inter-switch authentication protocols like SHAKEN/STIR, as each switch independently authenticates calls originating from it, achieving comprehensive detection without significant implementation complexity.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS10554821B1Identifying and processing neighbor spoofed telephone calls in a VoIP-based telecommunications network

Publication Date: 2020.02.04 ALVARIA INC

AI summary

A method for identifying and processing neighbor spoofed calls in a VoIP carrier's switching network where individual switches may be independently upgraded to authenticate calling party numbers using SHAKEN/STIR enabled switches. The switch ascertains a local routing number (“LRN”) of the calling party number for unsigned incoming calls to be terminated. If the LRN is that of the switch, and the call is unsigned, then the switch knows the call has a spoofed calling party number, and the switch may terminate the call as appropriate for a neighbor spoofed call. As the carrier enables others switches to be SHAKEN/STIR enabled, the terminating switch can determine the LRN for incoming calls and ascertain whether the call originated from a SHAKEN/STIR enabled switch. If so, the call should be signed. If not, then the switch processes the call as having a spoofed calling party number.