VoIP Call Validation via PSTN Knowledge for Spam Prevention

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Solution Overview

Problem

Voice over Internet Protocol (VoIP) spam and server overload issues in enterprise networks, where incoming VoIP requests can lead to unsolicited bulk messages and performance degradation due to the need for spam detection and rejection.

Innovation Solution

A system that validates VoIP call initiation messages based on demonstrated knowledge of Public Switched Telephone Network (PSTN) calls, using a processor and memory with computer code to store and transmit call data for authorization, and employs an authorization server to issue digitally signed tickets for trusted domains, limiting acceptance of VoIP calls from unverified sources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the system accepts incoming VoIP requests from any enterprise, then the VoIP communication coverage is improved, but the system becomes vulnerable to VoIP spam attacks

Engineering Contradiction:

ImproveVoIP communication coverageVSAvoidVoIP spam vulnerability

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary verification by checking whether the calling party has previously placed calls to the called party's enterprise through PSTN or prior VoIP calls. This preliminary action filters out spam callers before they can overload the system, while still allowing legitimate callers from any enterprise to communicate.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the system detects and rejects VoIP spam, then the spam protection capability is improved, but the server performance deteriorates due to overload

Engineering Contradiction:

ImproveSpam protection capabilityVSAvoidServer performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system uses a lightweight verification mechanism that checks only whether the calling party's identifier appears in a pre-established list of authorized callers (derived from historical call data). This copying approach avoids complex real-time spam analysis, providing effective spam protection while minimizing server processing overhead and maintaining high performance.

Inventive Principle:

Principle #26Copying

3Measurement precision

If the system validates every incoming VoIP request, then the spam detection accuracy is improved, but the call setup time increases

Engineering Contradiction:

ImproveSpam detection accuracyVSAvoidCall setup time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs verification checks in advance by maintaining a pre-computed list of authorized callers based on historical PSTN and VoIP call data. When a VoIP call arrives, the system only needs to check whether the caller's identifier exists in this pre-established list, rather than performing complex real-time analysis. This preliminary preparation enables accurate spam detection with minimal additional call setup time.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP2449744B1Restriction of communication in VOIP address discovery system

Publication Date: 2017.09.13 CISCO TECHNOLOGY INC

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AI summary

In one embodiment, a system is provided to restrict VoIP communication. The system may validate a Voice over Internet Protocol (VoIP) call initiation message based on demonstrated knowledge of a Public Switched Telephone Network (PSTN) call.