In a competitive environment, quality of service in voice telephony plays an increasingly important role both from a policy point of view and from a strategic point of view. Measuring, comparing and informing on quality of service will, therefore, become a standard activity by telecommunications operators and their regulators. Following a broad overview on the influence of liberalisation on quality of service, the paper reviews some of the main sources of information about quality of service for voice telephony (ITU, OECD, NRAs, telecommunication operators, etc.) and the methodological difficulties associated with an international comparison of quality of service. The paper will conclude with a comparison of currently published quality of service reports by telecommunications operators and provide some suggestions as to how these reports can help with strategic and tactical issues.