1849: Antonio Meucci demonstrates a communicating device to individuals in Havana. It is disputed if this is an electromagnetic telephone, but 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." If he reads Meucci's offer of collaboration, Manzetti does not respond.
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.
14 February 1876, about 9:30 am: 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 11:30 am: 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 1:30 pm: 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.
10 August 1876: Alexander Graham Bell makes the world's first long-distance telephone call, over a distance of about 6 miles, between Brantford and Paris, Ontario, Canada.
4 February 1878: Edison demonstrates the telephone between Menlo Park, New Jersey and Philadelphia, a distance of 210 kilometres (130 mi).
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 09:55am 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.