1849: Antonio Meucci demonstrates a communicating device to individuals in Havana. It is disputed that this is an electromagnetic telephone, but it is said to involve direct transmission of electricity into the user's body.
1854: Charles Bourseul publishes a description of a make-and-break telephone transmitter and receiver in L'Illustration, (Paris) but does not construct a working instrument.
1854: Meucci demonstrates an electric voice-operated device in New York, but it is not clear what kind of device he demonstrated.
1861: Johann Philipp Reis transfers voice electrically over a distance of 340 feet with his Reis telephone. To prove that speech can be recognized successfully at the receiving end, he uses the phrase "The horse does not eat cucumber salad" as an example because this phrase is hard to understand acoustically in German.
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."
1871: Meucci files a patent caveat (a statement of intention to file a patent application) for a Sound Telegraph, but it does not describe an electromagnetic telephone.
29 December 1874: Gray demonstrates his musical tones device and transmits "familiar melodies through telegraph wire" at the Presbyterian Church in Highland Park, Illinois.
4 May 1875: Bell conceives of using varying resistance in a wire conducting electric current to create a varying current amplitude.
2 June 1875: 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 voice-like 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.
For the timeline of the smart phone, see Smartphone.
14 February 1876, about 9:30am: Gray or his lawyer brings Gray's patent caveat for the telephone to the Washington, D.C. Patent Office (a caveat was a notice of intention to file a patent application. It was like a patent application, but without a request for examination, for the purpose of notifying the patent office of a possible invention in process).
14 February 1876, about 11:30am: Bell's lawyer brings to the same patent office Bell's patent application for the telephone. Bell's lawyer requests that it be registered immediately in the cash receipts blotter.
14 February 1876, about 1:30pm: Approximately two hours later Elisha Gray's patent caveat is registered in the cash blotter. Although his caveat was not a full application, Gray could have converted it into a patent application and contested Bell's priority, but did not do so because of advice from his lawyer and his involvement with acoustic telegraphy. The result was that the patent was awarded to Bell.
7 March 1876: Bell's U.S. Patent, No. 174,465 for the telephone is granted.
10 March 1876: Bell first successfully transmits speech, saying "Mr. Watson, come here! I want to see you!" using a liquid transmitter as described in Gray's caveat, and Bell's own electromagnetic receiver.
25 June 1876: Bell exhibits his telephone at the Centennial Exposition in Philadelphia, where it draws enthusiastic reactions from Emperor Dom Pedro II of Brazil and Lord Kelvin, attracting the attention of the press and resulting in the first announcements of the invention to the general public. Lord Kelvin describes the telephone as "the greatest by far of all the marvels of the electric telegraph".
10 August 1876: Alexander Graham Bell makes the world's first long-distance telephone call, one-way, not reciprocal, over a distance of about 6 miles, between Brantford and Paris, Ontario, Canada.
6 October 1877: the Scientific American publishes the invention from Bell – at that time still without a ringer.
25 October 1877: the article in the Scientific American is discussed at the Telegraphenamt in Berlin
November 1877: First permanent telephone connection in UK between two business in Manchester using imported Bell instruments.
12 November 1877: The first commercial telephone company enters telephone business in Friedrichsberg close to Berlin using the Siemens pipe as ringer and telephone devices build by Siemens.
1 December 1877: Western Union enters the telephone business using Edison's superior carbon microphone transmitter.
14 January 1878: Bell demonstrates the device to Queen Victoria and gives her an opportunity to try it. Calls are made to Cowes, Southampton and London, the first long-distance calls in the UK. The queen asks to buy the equipment that was used, but Bell offers to make a model specifically for her.
14 June 1878: The Telephone Company (Bell's Patents) Ltd. is registered in London. Opened in London on 21 August 1879, it is Europe's first telephone exchange, followed a couple of weeks later by one in Manchester.
12 September 1878: the Bell Telephone Company sues Western Union for infringing Bell's patents.
1886: Gilliland's Automatic circuit changer is put into service between Worcester and Leicester featuring the first operator dialing allowing one operator to run two exchanges.
1887: Tivadar Puskás introduced the multiplexswitchboard, that had an epochal significance in the further development of telephone exchange.
13 January 1887: the Government of the United States moves to annul the master patent issued to Alexander Graham Bell on the grounds of fraud and misrepresentation. The case, known as the 'Government Case', is later dropped after it was revealed that the U.S. Attorney General, Augustus Hill Garland had been given millions of dollars of stock in the company trying to unseat Bell's telephone patent.
1889: AT&T becomes the overall holding company for all the Bell companies.
2 November 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.
25 December 1900: John W. Atkins, the manager at International Ocean Telegraph Company (IOTC), a subsidiary of Western Union Telegraph Company made the first international telephone call over telegraph cable at 09:55 from his office in Key West to Havana, Cuba. Atkins was reported in the Florida Times Union and Citizen as saying, "For a long time there was no sound, except the roar heard at night sometimes, caused by electric light current." He continued calling Cuba and finally came back the words, clear and distinct: "I don't understand you."
1919: AT&T conducts more than 4,000 measurements of people's heads to gauge the best dimensions of standard headsets so that callers' lips would be near the microphone when holding handsets up to their ears.
1920 to 1969
16 July 1920: World's first radiotelephone service commences public service between Los Angeles and Santa Catalina Island.
11 April 1921: Opening of deep sea cable from Key West, Florida, to Havana, Cuba (115 miles).
22 December 1923: Opening of second transcontinental telephone line via a southern route.
1973: Bell Labs combined MOS technology with touch-tone technology to develop a push-button MOS touch-tone phone called the "Touch-O-Matic" telephone, which uses MOS integrated circuit chips and could store up to 32 phone numbers.