lecommunication systems. Another topic that many in the industry find difficult is the use of decibels and derived units. Appendix C provides the reader a basic understanding of decibels and their applications. The only mathematics necessary is an understanding of the powers of ten. To meet my stated objective where this text acts as a tutor for those with no experi- ence in telecommunications, every term and concept are carefully explained. Nearly all terminology can be traced to the latest edition of the IEEE Standard Dictionary and/or to the several ITU (International Telecommunication Union) glossaries. Other tools I use are analogies and real-life experiences. Examples are the train analogy for ATM (asyn- chronous transfer mode) and the short division experience with my younger daughter for quantization. We hear the expression "going back to basics." This book is back at the basics. It is written in such a way as to bring along the novice. Thus, the structure of the book is purposeful; later chapters build on earlier material. The book starts with some general concepts in telecommunications: What is connectivity? What do nodes do? From there we move onwards to the voice network embodied in the public switched telecommuni- cations network (PSTN), digital transmission and networks, and an introduction to data communications, followed by enterprise networks. It continues with switching and sig- naling, the transmission transport, cable television, cellular/PCS, ATM, and then network management. CCITT Signaling System No. 7 is a data network used exclusively for sig- naling. It was located after our generic discussion of data and enterprise networks. The novice would be lost in the explanation of System 7 without a basic understanding of data communications. I have borrowed heavily from my many years of giving seminars, both at Northeastern University and at the University of Wisconsin-Madison The advantage of the classroom is that the instructor can stop and reiterate or explain a sticky point. Not SO with a bo