Telephone

A telecommunications device that converts spoken sound into signals and reproduces them at a distance. Early telephones used electrical signals carried over wires; modern systems also use radio and digital networks.

Microphone: A transducer that converts sound into an electrical or digital signal. It captures speech at the transmitting end of a telephone.
Alexander Graham Bell: A Scottish-born inventor and speech researcher who received a foundational US telephone patent in 1876. His patent and demonstrations helped establish the telephone as a practical invention.
Public switched telephone network: The circuit-switched telephone system that connects public telephone subscribers worldwide. It carries ordinary calls between fixed-line and compatible mobile subscribers.
Telephone etiquette: Social conventions governing how people place, answer, and conduct telephone calls. The new medium required conventions for opening, managing, and ending remote conversations.
Telegraph: A system that transmits coded messages over distance using electrical or optical signals. Unlike a telephone, it traditionally carries encoded text rather than live speech.
Telephone receiver: A device that converts an electrical signal into sound near a listener's ear. It turns the incoming telephone signal back into audible speech.
Antonio Meucci: An Italian inventor who developed voice-transmission devices and filed a US patent caveat in 1871. His earlier work is central to disputes over the telephone's invention.
Mobile phone: A portable telephone that communicates with a network through radio links. It freed telephone service from a fixed wired endpoint.
Bell System: The network of companies that dominated US telephone service for much of the twentieth century. Its growth shaped access, infrastructure, and regulation of telephone service.
Videotelephony: Real-time communication that transmits both audio and video between distant participants. It extends the telephone call by adding a live visual channel.

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