The aim of this paper is to portray the development of the German telephone system as it resulted from the interaction among a set of corporate actors. The course of the development cannot be inferred from the impact of a single variable. On the contrary, system development is seen as the result of decisions (as well as of non-decisions), choices among a number of alternatives made by a definable set of actors. The choices made are constrained by the actual environment of the actors and by the sediment of previous decisions, but they are not determined by any of them.