Authentication threats in PSTN-VoIP architecture using multi-service gateways

Voice over Internet and more generally unified communication raised their importance in last decade as they are more and more reliable and robust. However as they gets more widely used, security issues became more noticeable and dangerous indeed. The objective is to give the reader a good overview and most relevant details about technologies used. This document provides architectures overview as well as authentication requirements needed for securing voice networks. Vulnerability analysis represents a core of this paper.