what is the basic priciple working of a telephone?

Answer 1

Basically the telephone has a microphone that changes your voice into electrical signals that are amplified and sent to the other person where they are changed back into sound with a device similar to a speaker...

Push Button phones use tones to tell the system what number is being pressed (each button generates two tones)...

Rotary phones (pretty much obsolete now) generate pulses that are detected by the system to know what number you dialed.. Rotary dial... is where the phrase "what number did you dial" comes from... even though we don't really dial numbers with push buttons anymore.

Answer 2

A Worm Is At Work - Slapp Happy & Henry Cow Finest Worksong - R.E.M. Bad Worker - The Replacements Brothers Gonna Work It Out - Public Enemy Julie's Been Working For The Drug Squad - The Clash Welcome To The Working Week - Elvis Costello

Answer 3

1849 Antonio Meucci demonstrates a device later called a telephone to individuals in Havana. (It is disputed if this is an electric telephone, but is said to involve direct transmission into the body.)
1854 Charles Bourseul publishes a description of a make-break telephone transmitter and receiver but does not construct a working instrument.
1854 Antonio Meucci demonstrates an electric voice operated device in New York, but it is not clear what kind of device he demonstrated.
1860 Johann Philipp Reis demonstrates a make-break transmitter after the design of Bourseul and a knitting needle receiver. Witnesses said they heard human voices being transmitted.
1861 The German Philipp Reis manages transfer voice electrically over a distance of 340 feet, see Reis' telephone.
1864 In an attempt to give his musical automaton a voice, Innocenzo Manzetti invents the 'Speaking telegraph'. He shows no interest in patenting his device, but it is reported in newspapers.
1865 Meucci reads of Manzetti's invention and writes to the editors of two newspapers claiming priority and quoting his first experiment in 1849. He writes "I do not wish to deny Mr. Manzetti his invention, I only wish to observe that two thoughts could be found to contain the same discovery, and that by uniting the two ideas one can more easily reach the certainty about a thing this important." If he reads Meucci's offer of collaboration, Manzetti does not respond.
1871 Antonio Meucci files a patent caveat (a statement of intention to patent).
1872 Elisha Gray founds Western Electric Manufacturing Company.
1872 Prof Vanderwyde demonstrated Reis's telephone in New York.
July 1873 Thomas Edison notes variable resistance in carbon grains due to pressure, builds a rheostat based on the principle but abandons it because of its sensitivity to vibration.
May 1874 Gray invents electromagnet device for transmitting musical tones. Some of his receivers use a metallic diaphragm.
December 29, 1874 Gray demonstrates his musical tones device and transmitted "familiar melodies through telegraph wire" at the Presbyterian Church in Highland Park, Illinois.
2 June 1875 Alexander Graham Bell transmits the sound of a plucked steel reed using electromagnet instruments.
1 July 1875 Bell uses a bi-directional "gallows" telephone that was able to transmit "indistinct but voicelike sounds" but not clear speech. Both the transmitter and the receiver were identical membrane electromagnet instruments.
1875 Thomas Edison experiments with acoustic telegraphy and in November builds an electro-dynamic receiver but does not exploit it.

11 February 1876 Elisha Gray invents liquid transmitter for use with a telephone, but does not build one.
14 February 1876 (about 9:30 am) Gray or his lawyer brings to the Patent Office Gray's caveat for the telephone. (A caveat was like a patent application without claims to notify the patent office of an invention in process.)
14 February 1876 (about 11:30am) Bell's lawyer brings to the Patent Office Bell's patent application for the telephone. Bell's lawyer requested that it be registered immediately in the cash receipts blotter.
Two hours later Elisha Gray's caveat was registered in the cash blotter. Although his caveat was not a full application, Gray could have converted it into a patent application, but did not do so because of advice from his lawyer and involvement with acoustic telegraphy. The result was that the patent was awarded to Bell.
7 March 1876 Bell's US patent 174,465 for the telephone is granted.
10 March 1876 Bell transmits speech "Mr. Watson, come here, I want to see you." using a liquid transmitter described in Gray's caveat and an electromagnetic receiver described in Gray's July 1875 US patent 166,095.
16 May 1876 Thomas Edison files first patent application for acoustic telegraphy for which US patent 182,996 was granted October 10, 1876.
10 August 1876 Alexander Bell makes worlds first long distance telephone call between Brantford and Paris, Ontario Canada.
October 1876 Thomas Edison tests his first carbon microphone.
20 January 1877 Edison "first succeeded in transmitting over wires many articulated sentences" using carbon granules as a pressure sensitive variable resistance under the pressure of a diaphragm (Josephson, p143).
30 January 1877 Bell's US patent 186,787 is granted for an electro-magnetic telephone using permanent magnets, iron diaphragms, and a call bell.
4 March 1877 Emile Berliner invents a microphone based on "loose contact" between two metal electrodes, an improvement on the Reis telephone, and in April 1877 files a caveat of an invention in process.
27 April 1877 Thomas Edison files telephone patent application. The US patents (474,230, 474,231 and 474,231) were awarded to Edison in 1892 over the competing claims of Alexander Graham Bell, Emile Berliner, Elisha Gray, A E Dolbear, J W McDonagh, G B Richmond, W L W Voeker, J H Irwin and Francis Blake Jr.[2]
Edison's carbon granules transmitter and Bell's electromagnetic receiver were used, with improvements, by the Bell system for many decades thereafter (Josephson, p 146).

4 June 1877 Emile Berliner files telephone patent application that includes a carbon microphone transmitter.
December 1, 1877 Western Union enters the telephone business using Thomas Edison's superior carbon microphone transmitter.
January 1878 First North American telephone exchange opened in New Haven, Connecticut.
4 February 1878 Thomas Edison demonstrates telephone between Menlo Park, New York and Philadelphia, a distance of 210 km.
14 June 1878 The Telephone Company Ltd (Bell's Patents) registered, London. Opened in London 21 August 1879 - Europe's first telephone exchange.
September 12, 1878 The Bell Telephone Co. sues Western Union for infringing Bell's patents.

Early months of 1879 The Bell Telephone Co. is near bankruptcy and desperate to get a transmitter to equal Edison's carbon transmitter.
1879 Bell merges with the New England Telephone Company to form the National Bell Telephone Company.
1879 Francis Blake invents a carbon transmitter similar to Edison's that saves the Bell company from extinction.
2 August 1879 The Edison Telephone Company of London Ltd, registered. Opened in London 6 September 1879.
10 September 1879 Connolly and McTighe patent a "dial" telephone exchange (limited in the number of lines to the number of positions on the dial.).
1880 National Bell merges with others to form the American Bell Telephone Company.
1882 A telephone company --an American Bell affiliate-- is set up in Mexico City.
1885 American Telephone and Telegraph Company AT&T is formed.
1886 Gilliland's Automatic circuit changer is put into service between Worcester and Leicester allowing for the first Operator dialing allowing one operator to run two exchanges.
13 January 1887 the Government of the United States moves to annul the patent issued to Alexander Graham Bell on the grounds of fraud and misrepresentation. Bell remanded for trial.
1889 AT&T becomes the overall holding company for all the Bell companies.
November 2, 1889 A. G. Smith patents a telegraph switch which provides for trunks between groups of selectors allowing for the first time, fewer trunks than there are lines, and automatic selection of an idle trunk.
10 March 1891 Almon Strowger patents the Strowger switch the first Automatic telephone exchange.
30 October 1891 The Strowger Automatic Telephone Exchange company is formed.
3 May 1892 Thomas Edison awarded patents for the carbon microphone against applications lodged in 1877.
3 November 1892 The first Strowger switch goes into operation in LaPorte, Indiana with 75 subscribers and capacity for 99.
27 February 1901 United States Court of Appeal declares void Emile Berliner's patent of the Bell telephone system
1915 Vacuum tubes used in coast-to-coast telephone circuits.
25 January 1915 First transcontinental telephone call, with Thomas Watson at 333 Grant Avenue in San Francisco receiving the call from Alexander Graham Bell at 15 Day Street in New York City.[1]
1919 AT&T installs the first dial telephones in the Bell System, in Norfolk, Virginia. The last manual telephones in the system were not converted to dial until 1978 when the last of the first bell phones were no longer made.