The scale of fraud in traditional telecommunications networks has deprived telecom operators of billions of euros each year, according to the Communication Fraud Control Association (CFCA). The problem is expected to increase with the continued migration to Voice over Internet Protocol (VoIP) — technology allowing audio communication over computer networks — particularly since such systems offer increased openness and vulnerabilities. The EU-funded project 'Scams and fraud detection in Voice over IP networks' (SCAMSTOP) worked on tackling these weaknesses of the relatively young technology. To protect VoIP providers from fraud and users from theft, the project envisioned a sophisticated fraud detection systems based on advanced monitoring, detection and alerting mechanisms in VoIP environments. Representing the core SCAMSTOP effort, innovative algorithms for misuse and fraud detection were formulated. The algorithms have been designed to achieve a high detection rate while using low processing power and memory resources. Work revolved around investigating the scope of fraud, classifying it, identifying specific problems in VoIP networks, and designing anti-fraud architecture. Types of fraud include subscription fraud (obtaining service with false identity and without paying) and superimposed fraud (obtaining resources from legitimate users by gaining access to their phone accounts). Fraudsters can also break into a PBX system and conduct what is known as mobile phone cloning. The solution created by the project team features many different components to identify fraud, representing a complete Fraud Management Solution (FMS) for VoIP networks. The system features a rich management interface complete with alarms and visualisation of results, enabling as well the creation of rules and the configuration of algorithms. SCAMSTOP is contributing significantly to knowledge in VoIP security and helps service providers earn their due revenue. It enables small and medium-sized enterprises (SMEs) to secure their infrastructure and protect themselves against fraudulent activities, helping to create more sustained development of Europe's VoIP sector. Numerous technologies, such as telephony, messaging and video conferencing, are set to benefit from this endeavour.