Telephones

Founded by Alexander Graham Bell, the telephone is a telecommunications device that transmits and receives sound, most commonly the human voice. It is one of the most common household appliances in the developed world, and has long been considered indispensable to business, industry and government. The word "telephone" has been adapted to many languages and is widely recognized around the world.

The device operates principally by converting sound waves into electrical signals, and electrical signals into sound waves. Such signals when conveyed through telephone networks — and often converted to electronic and/or optical signals — enable nearly every telephone user to communicate with nearly every other worldwide. Graphic symbols used to designate telephone service or phone-related information in print. The telephone used to transmit its electric signals via an analogue signal which was unreliable if the weather was windy and transmitted quite a poor quality of sound, now the sound is transmitted via a digital signal which is a lot more reliable and clear.