Structure of Telephone Set

Switchhook
Tells the exchange that you are going to make a telephone call or that a call has just been ended.
Dial
Sends the telephone number of the phone you want to call.
Ringer
Warns of an incoming call.
Transmitter
Converts audio signals to electrical signals.
Receiver
Converts electrical signals to audio signals.
Handset
The unit containing the transmitter and receiver is called a handset.