Information Leakage in Ubiquitous Voice-over-IP Communications

In VoIP, proxies are used by end-devices to perform a number of tasks including call setup and routing. Setup and routing is achieved through the exchange of call control messages which are forwarded among all involved proxies as well as the communicating end-devices. This paper will explore the information exchanged in Voice-over-IP (VoIP) call control messages and any possible implications this has on personal privacy. We assess the explicit and implicit deductions that can be made from handling messages in transit and evaluate these with a conceptual anonymity model. We aim to show that profiling is a threat in current VoIP implementations and that this threat becomes increasingly relevant with the growing adoption of VoIP. We consider these facts in light of possible future scenarios whereby VoIP has the potential to become a truly ubiquitous technology.