AT&T employees (from left) Edward Craft, 1st Lt. Ralph Bown, Maj. Nathan Levinson and Col. N. H. Slaughter watch an early aircraft-radio test. Many AT&T and Bell System employees entered the U. S.Army Signal Corps during World War I.

July 1917: The first air-to-ground and ground-to-air radio communications were accomplished by AT&T engineers at Langley Field in Virginia.

In the early days of aviation, pilots relied upon primitive means of communication during flight, including hand signals and flags. But during World War I, the U.S. military desperately needed radio communication between airplanes and the ground and between the planes themselves.

So in May 1917, General George Squier of the U.S. Army Signal Corps contacted Western Electric, AT&T's manufacturing subsidiary, to request an airplane radio telephone with a 2,000-yard range. On June 5, AT&T engineers met with the military to gather technical requirements, only to discover that there was practically no information about such essentials as the wavelengths desired, antennas and power supplies.

Undaunted and spurred on by wartime urgency, AT&T engineers designed the equipment using solid hunches, available circuitry and a few field tests. On July 2, they made their first air-to-ground transmission over a distance of about two miles. And on July 4, they accomplished a ground-to-air transmission over the same distance. By August 20, they had achieved two-way communication between planes in flight. Western Electric began shipping radio telephone sets abroad in October.

Although few of those sets ever actually saw service, AT&T had proved that rapid voice communication between military vehicles in the air or on the sea was possible.