# 1.3 Communications networks and signalling protocols

## What is a network?

#### While this book is not intended to be a definitive text on the networking aspects of communications systems, this section has been included to allow the main focus of the book – the design and performance of the modem, to be appreciated within the wider context of its place in the communications network. A very good text on networking has been written by Halsall (1992). The network is the all-embracing term for the collection of building blocks that make up a modern sophisticated communications system. It in general comprises physical interconnections via cable, fibre, radio or infrared, modems which process the information for reliable transmission through a given type of interconnection, and switches (routers, exchanges), which are used to route the information between source and destination. |

#### The end-user equipment, such as the telephone, fax or computer, is not usually considered to be part of the network, but rather a terminal which 'plugs into' the network.

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