Measurement and interpretation of voice traffic on the Internet

The Internet is being used to carry voice conversations. Sometimes the quality is acceptable, and at other times the voice is unintelligible. In this paper, we describe the results of a set of measurements on intrastate, cross country, and international Internet connections. The measurements are used to determine the relationships between the delay that is inserted to compensate for the variation in network delay, the strategy that is used to restore lost packets, and the “quality” of the voice connection. The “quality” of a connection is defined as the fraction of the time that a channel is free of distortion for intervals that are long enough to transmit active speech segments. We also examine the sensitivity of our quality measure to modifying the required length of the distortion free intervals. We have found that, with the proper combination of packet restoration, receiver delay and patience on the part of users, connections can be established that provide reasonably good voice connections, even during the busy period on the worse channel. Patience is required because a certain fraction of the connections are very bad. In which case the best strategy is to try again later. It is noted that the quality of international connections is not as good as cross country connections, which is not as good as the quality of intrastate connections. This indicates that Internet voice is better suited for local bypass than its current role as a replacement for long distance connections