Here's a broad, integrated view of existing communications technologies available world-wide -- including the Internet and Web, digital mobile telephony, ISDN, SMDS, frame relay, and ATM -- from a practical business perspective. Covering both private and public networks, the book offers a basic explanation of a wide range of technologies and describes their underlying principles and features, as well as the factors that differentiate them. The guide also showcases typical applications, exposes inherent limitations, explains pricing and methods of comparison, and discusses security pitfalls and protection systems.