The Information Age

World’s First Wireless Telephone Call

The world’s first wireless telephone call was made on Alexander Bell and Charles Tainter’s photophone (distant precursor to fiber-optic communications) from the Franklin School in Washington, D.C. to the window of Bell’s laboratory, 213 meters away.  The photophone used sunlight as a source and converted sound waves from ones voice into light.  The sound from your voice vibrated a hair thin mirror and sent the modified light rays to a receiver, which, using an element called selenium, produced sound from the reaction to the light waves.  The reaction was amplified by a set of batteries and was audible to the receiving party. This was considered the first form of completely wireless communication, and the first use of light to transmit information.
The photophone in use
The photophone in use. The top image is the sending unit and the bottom is the receiver.
For other milestones in wireless telephone communication, see:
Source: Alexander G. Bell, “On the Production and Reproduction of Sound by Light,” The American Journal of Science 20 (July to December 1880): 305-324.
Image Source: The Great Geek Manual, “The Photophone,” This Day in Geek History, (accessed September 17, 2011).