History Of Telephone Communication System

     Telephone is an instrument of transmitting human voice over a distance using wires or radio by converting sound vibrations into an electric signals. The word telephone was originated from the Greek words 'tele' means far and 'Phone ' means sound, so telephone means sound at distance or to a distance. Telephone provide the common method of talking to people at a distance. An art or science of construction a telephone is known as telephony.
     Alexander Graham Bell (A Scotsman who settled in the united states ) invented the telephone in Boston, U.S.A. In 1876 Bell, Watson, Gardiner, Hubbard and Thomas Sanders formed the Bell telephone company in 1877. In 1878 the first telephone exchange opened in New Haven,U.S.A. In 1880. The American Bell Telephone Company was formed. The first commercial long distance telephone line opened in 1881, 72 kilometer between Boston and Providence, Rhonde island, U.S.A. In 1891 American scientist Almon B. Strowger developed an automatic step by step switching system. In 1897 the first dial telephone become operational. In 1907 electron tube was developed and was adapted as an amplifier in 1912. In1947 the transistor was invented. This tiny device require less power and space is used in 1955. In 1961, Bell scientist developed LASER to communicate on cables. In 1960 United state began launching communication satlite. In 1970 International Direct dialing began operating between New York and London. In 1980 a first optic system for transmitting local calls are used in 1990 cordless, cellular radio and cellular mobile telephones are developed in 1990,s different value added services are added to telephony and an International computer network gets fully developed and everything becomes available with a click of mouse.
     Telecommunication is the transmittion as well as reception of information in the form of voice, data, video or images across a distance over a medium from transmitter to receiver. The word 'Communicate ' comes from the Latin root meaning to make common. Telecommunication networks carry information signals among entities which are geographically for a part and entity may be a human being, a computer, a machine, a telephone . In telephone conversation the one who initiates the call is known as 'a Calling Subscriber' or 'calling party' and the one who receives the call or the one whom call is made is known as 'a called subscriber ' or ' a called party.'