The present day myth is that a Scottish born inventor called Alexander Graham Bell invented the telephone. In another room, Watson, next to the receiver, heard clearly the first telephone message: "Mr. Watson, come here; I want you."
A few hours after Bell had patented his invention, another American inventor, Elisha Gray, filed a document called a caveat with the U.S. Patent Office, announcing that he was well on his way to inventing a telephone. By definition a telephone is any mechanism capable of conduction sound for a great distance. The earliest telephones were mechanical devices based on sound transportation through air or other physical media rather than electrical devices depending on electro-magnetic signals.
The lover's telephone (or string telephone) has also been known for centuries, connecting two diaphragms with string or wire which transmits the sound from one to the other by vibrations along the string and not through electric current.
Electro-magnetic transmitters and Antonio Meucci
Meucci invented a paired electro-magnetic transmitter and receiver, where the motion of a diaphram modulated a signal in a coil by moving an electromagnet. Meucci is also credited with the early invention of the anti-sidetone circuit, and of inductive loading of telephone wires to increase long-distance signals. Meucci demonstrated some sort of instrument in 1849 in Havana, Cuba, but the evidence is unclear if this was an electric telephone or a variant on the string telephone using wires. Meucci was recognised as the first inventor of the telephone by the United States Congress, in its resolution 269 dated 11 June 2002.
Johann Philipp Reis
The Reis transmitter was a make-break transmitter. Reis' invention is best known then as the "musical telephone". That is, a needle attached to a diaphram was alternately pressed against, and released from a contact as the sound moved the diaphram. This make-or-break signaling was able to transmit tones, and some vowels, but since it did not follow the analog shape of the sound wave (the contact was pure digital, on or off) it could not transmit consonants, or complex sounds. This can be called a "telephone", since it did transmit sounds over distance, but is hardly a telephone in the modern sense, as it failed to transmit a good copy of any supplied sound.
Poul la Cour
Around 1874 Poul la Cour, a Danish inventor, experimented with audio telegraphs on a line of telegraph between Copenhagen and Fredericia in Jutland. Again, la Cour made no claims of transmitting voice, only pure tones. Elisha Gray
Gray's 'harmonic telegraph,' with vibrating reeds, was used by the Western Union Telegraph Company. Gray's harmonic telegraph apparatus follows in the track of Reis and Bourseul ? that is to say, the interruption of the current by a vibrating contact. Bell used a Gray liquid transmitter for many of his early public demonstrations. Thomas Edison and Carbon Grain transmitter
Thomas Alva Edison took the next step in developing telephonic fidelity with his invention of the carbon grain transmitter. Edison discovered that carbon grains, squeezed between two metal plates had a resistance that was related to the pressure, thus, the grains could vary their resistance as the plates moved in response to sound waves, and reproduce sound with good fidelity, without the problems associated with a liquid contact. This style of transmitter remained standard in telephony until the 1980s, and is still produced. Bell's background
As Professor of Vocal Physiology in the University of Boston, Bell was engaged in training teachers in the art of instructing deaf mutes how to speak, and experimented with the Leon Scott phonautograph in recording the vibrations of speech. This apparatus consists essentially of a thin membrane vibrated by the voice and carrying a light stylus, which traces an undulatory line on a plate of smoked glass. The line is a graphic representation of the vibrations of the membrane and the waves of sound in the air.
This background prepared him for work with sound and electricity. Bell, with his assistant Watson discovered that the movements of the reed alone in a magnetic field could transmit the modulations of the sound. The first long distance telephone call was made on August 10, 1876 by Bell from the family homestead in Brantford, Ontario to his assistant located in Paris, Ontario, some 16 km (10 mi.) distant.
Summary of Bell's achievements Bell adopted Gray's, and later Edison's resistive transmitters and adapted switching plug boards developed for telegraphy by Western Union. Additionally, Bell succeeded where others failed to assemble a commercially viable telephone system. It can be argued that Bell invented the telephone company.