The purpose of this book is to use tools from game theory to examine stakes in the telecommunications industry. Are examined: (1) the easiness (or uneasiness) of consolidation (2) "beauty contests" (3) the problems of leadership (4) the management of QoS (Quality of Service) by operators (5) the appearance of little crowds of buyers and vendors (6) transport and e-commerce. The results of these models are of three kinds: (1) they are in accordance with intuition (2) there are paradoxical (3) they suggest that some problem has to be solved by practitioners. The goal of game theory is not to predict the behaviors accurately. The models from game theory display the effects which matter and show their relative strength. Game theory should be used to "provide ideas" (Ariel Rubinstein). So theorists should be interested by this book. But it could attract the attention of practitioners, too.