Real-time traffic is an important issue when designing networks. The growth in the deployment of voice applications in packet switched networks requires that the network can guarantee a minimum level of quality. At the same time, customers want guaranties that the proper Quality of Service is provided for their contracted services. In this environment service providers need means of reporting the quality level of their networks.

Standardisation bodies define general metrics, such as delay, jitter or losses without giving detailed information regarding the actual user?s perception of the traffic. Other approaches such as the Mean Opinion Score (MOS), are too coarse to be significant on best-effort based environments such as the Internet.

This work is motivated by the potential change in the Quality of Service (QoS) parameters found in packet switched networks. Which highlights the inaccuracy of metrics such as MOS, since they were designed for the stable circuit switched networks.

This paper proposes a novel approach to on-line voice quality measurement which is more suitable for packet switched networks than the classical alternatives, while keeping the subjective approach of MOS. Moreover, our solution permits the real-time reporting of the voice communication?s quality.

Along with the specification of this metric, the paper provides an experimental validation of the proposal using a real testbed with real applications. The results show the higher accuracy in reporting using this proposal over the standard metrics currently used.