Assessment of VoIP quality over Internet Backbones

As the Internet evolves into a ubiquitous communication infrastructure and provides various services including telephony, it will be expected to stand up to the toll quality standards set by traditional telephone companies. Our objective in this paper is to assess to what extent today’s Internet is meeting this expectation. Our assessment is based on delay and loss measurements taken over wide-area backbone networks, considers realistic VoIP scenarios and uses quality measures appropriate for voice. Our findings indicate that although voice services can be adequately provided by some ISPs, a significant number of paths lead to poor performance even for excellent VoIP end-systems. This makes a strong case for special handling of voice traffic on those paths. Even on the good paths, rare loss events can occasionally cause perceptible degradation of voice quality. Finally, the appropriate choice of the playout buffer scheme for each path was found to be of critical importance for the perceived quality.