Book excerpt: Telecommunications Essentials, Second Edition, provides a comprehensive overview of the rapidly evolving world of telecommunications. Providing an in-depth, one-stop reference for anyone wanting to get up to speed on the $1.2 trillion telecommunications industry, this book not only covers the basic building blocks but also introduces the most current information on new technologies. This edition features new sections on IP telephony, VPNs, NGN architectures, broadband access alternatives, and broadband wireless applications, and it describes the technological and political forces at play in the world of telecommunications around the globe. Topics include Communications fundamentals, from traditional transmission media, to establishing communicationschannels, to the PSTN Data networking and the Internet, including the basics of data communications, local area networking, wide area networking, and the Internet and IP infrastructures Next-generation networks, including the applications, characteristics, and requirements of the new generation of networks that are being built to quickly and reliably carry the ever-increasing network traffic, focusing on IP services, network infrastructure, optical networking, and broadband access alternatives Wireless networking, including the basics of wireless networking and the technologies involved in WWANs, WMANs, WLANs, and WPANs