A commercial VoIP system based on MPLS technology and intended for use in closed networks, has been analyzed from the point of view of security. The security requirement in this project drives from scenarios of use within a large company with a special need for secure voice and data transmissions. The analysis illuminates the specific requirements for DONG Energy; the largest energy supplier in Denmark, and as such a part of the nations critical infrastructure, but it also discusses the general aspects of security in VoIP systems of this type.

The "Security in VoIP systems" project was completed in 2005, at the Danish Technical University in Lyngby Denmark, with special thanks to Robin, Amit and Waqas from IMM and Sten from DONG Energy.