This is a paperback. A great beginner's guide. Explains basic analog telephony (the "old" technology) and takes you into current generation data networking & communications. Easy to follow and yet it provides a good understanding of today's core communications technologies. I relied upon it as a Technology Investment Banker (ie, my clients were tech co's) to understand the products & services of my clients; i.e., the servers, routers & switches they manufactured. This book gave me that understanding by providing the "big picture" re: the forces & technologies that brought us from a voice/analog world to the digital/data landscape of today.