Canon FACSIMILE BASIC 2000 Service Manual page 26

BASIC OF TELEPHONE
In this way, a telephone network consists of telephones used as a terminal
for converting voice to electrical signals and electrical signal back again to
voice, a telephone line for transmitting electrical signals to places far away,
and an exchange system for connecting two telephones.
Telephone lines come in various types: coaxial cable, optical fiber cable,
microwaves communications satellites and submarine cable.
The places where the exchange system is located is called the telephone
center (or the exchange center).
1–18
Satellite
communication
system
Transit
exchange
Subscriber
exchange
Telephone
Voice
Electrical signal
Fig. 1-20 Telephone Network Organization
Electrical signal
Telephone
Subscriber
exchange
Transit
exchange
Submarine
cable system
Voice