Page 29 - Intelligent Communication Systems

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COMMUNICATION

NETWORK STRUCTURE

The telephone network was constructed as a communication network. Using the
network, telephone service was provided. Advances in information processing
technology and new communication services such as data communication service
and facsimile communication service have been implemented by using the tele-
phone network. To interconnect terminals, computers, and networks, the network
architecture and protocol have been developed. In this chapter, the network archi-
tecture of the telephone network is described, as is the network architecture and
protocol of the computer network.

3.1 TELEPHONE NETWORK ARCHITECTURE

The conventional telephone network structure is shown in Figure 3.1. The con-
ventional telephone network has been hierarchically structured. There are toll switch-
ing (TS) systems and local switching (LS) systems. When phone A calls phone B,
the call is transmitted through LS-TS-TS-TS-TS-LS. With advances in telecommu-
nication network, the network structure became simple. A two-layered structure

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