With the advent of new technologies and recent changes in regulations and economies, telecommunications services have grown chaotically. This article describes a taxonomy which uses common terms and concepts to classify the services and features available in telecommunications systems, for planners and policy makers. The structure provides a common basis for Europeans in particular to discuss the formation of new broadband telecommunications networks. It can also be used to identify areas of R&D and to plan future services. As an example, the authors apply the taxonomy to suggest the kinds of elements, properties and rules which might form the basis of a taxonomy knowledge base in telecommunications systems.