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Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas pigeon post is not. Ancient signalling systems, although sometimes quite extensive and sophisticated as in ...
The telegraph represented a disruptive innovation in the history of the United States from its invention in the 1830s onward by quickly becoming a vital part of the nation's communication infrastructure. Its relative importance declined with the spread of telephones in the 20th century. Telegraph service permitted short texts to be sent cheaply ...
Telecommunication systems are occasionally "duplex" (two-way systems) with a single box of electronics working as both the transmitter and a receiver, or a transceiver (e.g., a mobile phone). [41] The transmission electronics and the receiver electronics within a transceiver are quite independent of one another.
Hughes telegraph, an early (1855) teleprinter built by Siemens and Halske. Electrical telegraphy is a point-to-point text messaging system, primarily used from the 1840s until the late 20th century. It was the first electrical telecommunications system and the most widely used of a number of early messaging systems called telegraphs, that were ...
A telephone number serves as an address for switching telephone calls using a system of destination code routing. [1] Telephone numbers are entered or dialed by a calling party on the originating telephone set, which transmits the sequence of digits in the process of signaling to a telephone exchange. The exchange completes the call either to ...
The telephone played a major communications role in American history from the 1876 publication of its first patent by Alexander Graham Bell onward. In the 20th century the American Telephone and Telegraph Company (AT&T) dominated the telecommunication market as the at times largest company in the world, until it was broken up and replaced by a system of competitors.
An old rotary dial telephone. AT&T push button telephone made by Western Electric, model 2500 DMG black, 1980. A telephone, colloquially referred to as a phone, is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically ...
Telephony (/ təˈlɛfəni / tə-LEF-ə-nee) is the field of technology involving the development, application, and deployment of telecommunications services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is intimately linked to the invention and development of the telephone.