The Telephone
A telephone network establishes a voice communication path between any two telephones within the network.
Telephone contains converters which convert the audible sound signals into electromagnetic signals that can be sent through the telephone network (and electromagnetic signals to audible sound signals at the other end).
Microphone converts mechanical vibrations in the air (sound waves) into electrical signals for transmission in an electrical circuit
Telephone speaker changes the electrical voice signals back into audible sound by magnetically vibrating a diaphragm that is synchronized with the incoming electric voice signals
In a dial-pulsing telephone the rotary dial generates electrical pulses on the telephone line by opening and closing an electrical relay when the dial is turned and released.
Tone-dialing telephone uses a technique called dual tone multifrequency (DTMF) Touch-Tone dialing.