Telecommunications Trunking

Abstract

When research began in modern optical fiber technology in the late 1960s the most important application envisioned was in the replacement of metallic cables (containing twisted wire pairs) which carry telephone circuits between telephone buildings. Figure 7-1 is a simplified diagram of a telephone network. The wires which run from a customer’s premises to a telephone building are called loops. The circuits which go between telephone buildings (over wires or other media) are called trunks. Within the telephone building requests for service are answered by using a switching machine to connect the customer’s loop to the required trunk (to carry the call to its destination). Thus, while loops are dedicated to the customer (except for party lines), trunks are shared by all customers and allocated when needed.