Diagram: Reis' telephone
Reis' telephone
1861
Diagram: Alexander Graham Bell realizes that sound can be transmitted as a continuous electrical wave.
Alexander Graham Bell realizes that sound can be transmitted as a continuous electrical wave.
1875
Diagram: Berliner develops improved telephone transmitter (microphone)
Berliner develops improved telephone transmitter (microphone)
1877
Diagram: Bell acquires Edison's carbon button amplifier microphone patents from Western Union
Bell acquires Edison's carbon button amplifier microphone patents from Western Union
1879
Diagram: Gray patents the coin-operated payphone mechanism
Gray patents the coin-operated payphone mechanism
1889
Diagram: Bell long distance circuits map
Bell long distance circuits map
1891
Diagram: The U.S. has most of the world's telephones
The U.S. has most of the world's telephones
1929
Diagram: Anti-sidetone circuit developed
Anti-sidetone circuit developed
1930
Diagram: AT&T World Radio Telephone Chart
AT&T World Radio Telephone Chart
1930
Diagram: Map of Bell System Overseas Telephone Circuits
Map of Bell System Overseas Telephone Circuits
1933
Diagram: Pie chart of Western Electric wartime production
Pie chart of Western Electric wartime production
1944
Diagram: Transatlantic telephone cable (TAT-1)
Transatlantic telephone cable (TAT-1)
1956