This research presents an analysis of the European Telecommunication strategic environment with particular focus on the three macro-changes which have been influencing the recent history of such industry. These are, first of all, the shift from a government-controlled market to a privatized market. Second, the introduction of price limitations - called Eurotariff - which are supposed to regulate the mobile traffic throughout Europe. Finally, the constant growth of data and internet traffic demand, compared to the voice traffic demand, mainly due to the success of OTTs (Over-the-Tops) and the introduction of NGN (Next-Generation Network) applications and software. Such changes have increased the competition in an industry which was organized in monopolies and are forcing the companies to change, following the different customers' needs. Throughout the essay, a case study about Telefónica has been developed: after a presentation of the company and of Telefónica's deregulation process, the consequences of the environment analysis will be defined and, finally, some strategic actions will be proposed in order to adapt to the new strategic environment. The methodology which has been followed consists in a research on the models existing in literature designed to analyze the strategic environment. The best ones have been used and applied to the real case, involving Telefónica: the findings obtained have then been considered the basis to define the strategic actions. The purpose of the paper is twofold: first of all to offer an understanding of the telecommunications business with a particular focus on the Eurotariff, OTTs and NGN phenomena; second to show how a strategic environment can be effectively studied, focusing on the changes that characterize the industry, and how the consequences can be deduced. The information coming from this type of studies is very important for a company to understand what to change in order to adapt to a new context and achieve better performances.