How green is IP-telephony?

Abstract

With constantly increasing costs of energy, we ask ourselves what we can say about the energy efficiency of existing VoIP systems. To answer that question, we gather information about the existing client-server and peer-to-peer VoIP systems, build energy models for these systems, and evaluate their power consumption and relative energy efficiency through analysis and a series of experiments. Contrary to the recent work on energy efficiency of peer-to-peer systems, we find that even with efficient peers a peer-to-peer architecture can be less energy efficient than a client-server architecture. We also find that the presence of NATs in the network is a major obstacle in building energy efficient VoIP systems. We then provide a number of recommendations for making VoIP systems more energy efficient.