Book excerpt: Volume 2 of TERB 3ed covers the convergence of telephony and data transport, including wireless networks. Now that data is becoming the predominant source of traffic more efficient multiplexing schemes and more flexible control methods are needed in the transport network, such as giving the customer the ability to call for bandwidth on demand. With the development of control methods for switched data services it is now recognised that improved ways to control the transport network are possible and standards initiatives are taking place to establish and improve the network control layer. Detailed explanation of propagation in wireless and optical fibre systems requires a substantial amount of mathematics, also covered in this volume. For each of the math chapters there is an explanation of why the mathematics is important, where it is applied and references to other chapters.