Modeling and assessing secure Voice over IP performance

Abstract

Voice over Internet Protocol (VoIP) systems enable efficient communications over data networks, but security of VoIP and the impact of that security on communications quality has not been quantitatively modeled. A conversational model is adapted for VoIP and a computational model of communication quality - the Z-Model - is developed. VolIP conversations are simulated for networks with a range of performance characteristics including differing bandwidth, latency and bit error rates to evaluate the impact of security on communication quality. Results show that improving conficlentiality via encryption of conversation data packets does not introduce significant delays, but does increase bandwidth. In certain restricted-bandwidth environments this results in dramatic reductions of perceived conversation quality.