Telephones

Instruments, apparatus, or devices that convey or reproduce sounds at a distance, especially such devices in which the human voice is transmitted as by wire, satellite, or via base-station antennas as short-wave analog or digital signals. The term was used as early as the 18th century to refer to string phones (cups joined by a string), but the modern device is attributed to Alexander Graham Bell, who patented it in March 1876. That original telephones worked on the principle that sounds of speech are complex vibrations in air, which can be transferrable to solid bodies and in electrical impulses in conducting metals.