ocol End-user Telecom business Network Figure 1.5 The multi-angle view of this book Understanding Changing Telecommunications - Building a Successful Telecom Business Flow of main tasks in the case study Telecom business actor 1 Roles Business plan 2 End-user Processes Identify segments Technical plans revenue oppor- tunities Elaborate service plan Implement service Identify solutions Implement infrastructure Network Figure 1.6 Case study flow The commonly applied technical and vertical focus has changed to a more horizontal techno-economic one, reflecting the increased power of the user and the overall uncer- tainty. In the prevailing situation it seems sometimes wiser to be humble and indicative than to be precise. The book then becomes a framework for understanding how progress can be achieved, based on a top-down techno-economic approach. In line with this it focuses on success factors in the user network and user-business interface, especially services including implementation, charging, quality and security. Services and the service layer are described in detail because of their increasing importance from a business point of view. Fundamental technical plans are the most important tool used to explain the technical context, that is, when vertical networks turn into a horizontal network. Such plans offer a layered end-to-end approach. The book focuses on the core network rather than on the access network. The reasons are the following: The paradigm shift is faster in the core network parts than in the access parts. At the same time the core converges whereas the number of access alternatives increases as new technologies are developed for existing media (new mobile systems, xDSL (a family of digital subscriber lines), power-line systems, WLAN (wireless local area networks) etc.). It is not possible to cover all access alternatives with any depth within the frame of this book. An access system overview is provided in Chapter 13. The goal is to enable connection of all different accesses including WLAN to the 