El libro constituye una completa introducción a las telecomunicaciones, presenta los fundamentos básicos de las telecomunicaciones, explica los conceptos elementales para entender el funcionamiento de las señales y los diferentes dispositivos utilizados en la transmisión de voz, datos o imágenes, las tecnologías, protocolos, y servicios que se emplean en las redes telefónicas, así como la legislación que los regula, constituyendo una referencia obligada para todo estudiante y profesional. (Description in English below). Description in English: The book presents the basic fundamentals of Telecommunications, explains the elementary concepts to understand the operation of the signals and the different devices used in the transmission of voice, data or images, the technologies and protocols that are used in telephone networks -fixes and mobile-, in the data -both local and extended area-, and the services that are provided on these, as well as the legislation that regulates them, constituting an obligatory reference for all those students and professionals who want to enter an exciting world and of so much future. All this is explained in a clear and simple way, but at the same time rigorous, with a methodology based on the experience that the author has been accumulating as a writer and teacher for more than thirty years. The book, which is a complete introduction to Telecommunications, is structured in six chapters, which develop the following contents: o Characteristics of the message: sound, data and imageso Analog and digital signals. Compression of sound and videoo Radio and televisiono Transmission technologies. PDH, SDH and GPONo Optical fiber (WDM) and microwaveso Communications satellites. VSAT and GPS systemsoCommon telecommunication infrastructures (ICT)o Switching and multiplexing techniqueso Modulation. Modems and interfaceso LAN and WAN networks. Interconnectiono X.25 Protocol, Frame Relay, ATM and TCP / IPo Broadband technologies: ADSL, VDSL, FTTHo The IP protocol. Internet and the WWW. VoIP and IPTVo The switched telephone network. ISDN and PBXo The radio spectrum. Antennas and radiationso Mobile communications. GSM, GPRS, UMTS and LTE, etc.o Wireless networks: Wi-Fi, Bluetooth, RFID, WiMAX, etc.o Legislation. General Telecommunications Law. At the end of the book there is an extensive glossary of terms and an extensive list of bibliographical references, very useful for the reader interested in expanding their knowledge.