that with- out experience and a good mental model of the actual hardware technology, no effi- cient design methodology could be advised. So, I started looking for a general model that could provide us with the concepts, the modelling language and the methods that could make us more productive in telecom system development and knowledge management. A number of experiences during the 1980s led me to the general system model I was looking for. While attending a course on "General Systems Theory" at Stock- holm University, where "living systems" (cells, organs, humans, groups and orga- nizations, see Miller (1978)) was a key subject, I realized that through the introduction of computer-controlled functions in systems, we have the opportunity Preface to design telecommunication systems that are responsive, intelligent, adaptive and autonomous, if not self-healing, i.e. behave more and more like a living system. An important aspect of living systems is that they are processing systems, which, as a result of communication with other systems in their environment, produce some utility. The characteristics of living systems are upheld by the existence of a pro- cess control subsystem (called "decider" by Miller), that controls the resources used to produce the utility. To handle the complexity of the system, process control is often performed on a number of echelons. By applying this view to telecom systems, it was not difficult to see that a tele- com system is a processing system in the same sense: The utility that is provided is information transfer (you enter information in some entrance to the system, and the same information comes out at some other exit). To produce this utility, the telecom system communicates with its end-users, with system operators and with other cooperating telecom systems. The bulk of the software in a telecom system deals with process control. There are two major control structures (structures of "echelons"): control of service provisioning, as a result of end-user requests, and control of sys