Canon fax basic 2000 Manuale Di Servizio

BASIC OF TELEPHONE

1–20

As the transit exchange relay-switches conversations between subscriber

exchange, we can consider transit exchange to be ranked (classified)

higher than the subscriber exchange. The rank for an exchange is called the

grade, and the telephone center is called the center grade. That is, the high

grade exchanges can route calls to a wider area.

Fig. 1-23   Center Grade

5.3

Nationwide Telephone Network (In case of Japan)

The nationwide network in Japan can be divided into subscriber areas

matched with administrative districts. A subscriber area has more than one

subscriber exchange to connect all the telephones in the area.

A call within the area is called a local call, and can be made by dialing an

exchange number and the subscriber number.

Fig. 1-24   Subscriber Area and Local Call

Transit exchange

Subscriber exchange

Telephone

Exchange

Local call

Subscriber area