This longitudinal analysis of the modernization of a public service network highlights the “great transformation” of France Télécom, the public utility which gradually became a firm in a highly competitive market. By detailing the computerization of the installation and sale of telephone products, this article reveals the organizational and technical nature of the service relationship based on successive assessments of the recipient – as subscriber, user, consumer and client. Hence the article identifies a series of rationalizations (organizational, technical and professional) which reflect management efforts to adjust to the increasing sophistication of telephone service in such areas as data processing, definition of procedures, and coordination of technical and commercial activities. We see a dialectic developing between relevance and consistency of information, coupled with a recurring tendency between centralization and decentralization in the approach to organizing information, i.e. whether to pick up adequate information or, by contrast, to consolidate it. In fact, the computerization process examined here reveals a more general dynamic of business organisations which is characterized by attempts on the part of management to reduce environmental uncertainties, and thereby promote technical and organizational innovations which might provide more flexibility and strength in confronting such uncertainties.