AbstractThis paper describes aspects of a project in which a computer model (I.C.D.M.) of the longer-term trends in demand for telecommunications media in the U.K. was developed and implemented. The work was undertaken by Cambridge University Engineering Department for the Long Range and Strategic Studies Division of British Telecom. The paper concentrates on the processes of developing and implementing the model as an aid in the formulation of robust investment and marketing strategies for British Telecom in the face of a rapidly changing technological environment and emergent competition. The value of the integrative and dynamic characteristics of the I.C.D.M. in this context is emphasized, and the role of a user-friendly colour graphics interface in encouraging managerial acceptance of the new tool is noted.