This book is the study guide and textbook for the TCO Certified Telecommunications Network Specialist (CTNS) Certification, conforming to the lessons in the eight CTNS courses and their exams: 2241 Introduction to Broadband Converged IP Telecom, 2206 Wireless Telecommunications, 2221 Fundamentals of Voice over IP, 2201 The PSTN, 2212 OSI Layers and Protocol Stacks, 2211 LANs, VLANs, Wireless and Optical Ethernet, 2213 IP Addresses, Packets and Routers, and 2214 MPLS and Carrier Networks. The selection of material, its order, timing, and explanations are field-tested to deliver the core knowledge set for today’s telecommunications. The courses deliver a solid foundation of knowledge in broadband, telecom, datacom and networking: the fundamentals, technologies, jargon and buzzwords, standard practices and most importantly, the underlying ideas, and how it all fits together… with TCO Certification to prove it! The first four CTNS courses begin with Broadband Converged IP Telecom, an introduction and first pass through all of the topics; followed by Wireless Telecommunications, including 5G and Wi-Fi 6, then Introduction to Voice over IP, and rounded out with The PSTN. The next courses in CTNS deliver a practical understanding of telecom networks and the three enabling technologies: Ethernet and its MAC frames, IP packets with IP addresses and routers, and the traffic management system MPLS. We begin with the OSI Layers to organize the discussions. This book is intended to enhance your learning and retention while taking the online courses. It is also useful as a day-to-day reference handbook and glossary. Our goal is to explain the big picture, the jargon and buzzwords, and put in place a very solid base of telecom knowledge spanning fundamentals to the latest technologies and how they are deployed – in plain English.