FLASH CALLS IN MODERN TELECOMMUNICATION NETWORKS: THREATS, CHALLENGES, AND EFFECTIVE COUNTERMEASURES

DOI: 10.31673/2786-8362.2025.014820

Abstract

This paper addresses the phenomenon of Flash Calls — ultra-short incoming
calls used for user authentication in modern telecommunication networks — and their impact on network
security and operator revenues. Unlike traditional SMS-based methods, Flash Calls allow cost-effective,
high-speed verification, but simultaneously bypass billing systems and facilitate fraudulent practices such
as CLI spoofing and international revenue sharing fraud (IRSF). The paper explores the technical
characteristics of Flash Calls, highlights their detection complexity, and analyses vulnerabilities in current
anti-fraud systems. A multi-layered countermeasure architecture is proposed, integrating real-time
analytics, machine learning algorithms, and STIR/SHAKEN protocols to identify and block fraudulent
activity. The effectiveness of the approach is supported by traffic analysis and experimental blocking results
on global platforms such as Meta. The proposed system ensures reliable identification of malicious patterns
while minimizing false positives and preserving service quality.
Keywords: Flash Calls, CLI spoofing, fraud detection, Voice firewall, Wangiri, machine learning,
STIR/SHAKEN, telecom security, IMS network

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