SIAHST_120621_362
Existing comment: Alexander Graham Bell's big box telephone
1876
one of the first commercially available telephones

Telegraph lines could carry only one coded message per wire at a time, which became a hindrance as the volume of communication increased. To overcome this problem, Alexander Bell used his knowledge of acoustics to devise a method of sending multiple tonal messages over a wire. This led to the telephone, and a communication revolution that transformed business and daily life.
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