telephone

The telephone is a telecommunications device that is used to transmit and receive electronically or digitally encoded sound between two or more people conversing. It is one of the most common household appliances in the developed world today. Most telephones operate through transmission of electric signals over a complex telephone network which allows almost any phone user to communicate with almost any other user.

The telephone consists of an alerting device, usually a ringer, that remains connected to the phone line whenever the phone is "on hook", and other components which are connected when the phone is "off hook". These include a transmitter microphone, a receiver speaker and other circuits for dialing filtering and amplification.