1627 - The idea of the phone is predicted.
1854 - Sound being transmitted is studied.
1876 - The invention of the telephone.
1886 - AT&T offers private line service.
1915 - First transcontinental call.
1946 - First mobile telephone service.
1962 - Cell technology shown to the FCC.
1970 - The first picture phone is created.
1978 - First service trial of Bell.
1980 - Digital cell technology.
2005 - Over 50% of adults now own a cellular phone, and growing!

How it works
The telephone is an electrical instrument. Speaking into the handset's transmitter or microphone makes its diaphragm vibrate. This causes the receiver's diaphragm to vibrate. It uses electric microphones for the transmitter and piezoelectric transducers for receivers. The mechanical parts of a sound wave convert into an electrical signal.