Titi

Phone
The phone is a telecommunications device designed to transmit sound signals through electrical signals remotely.
For a long time was considered Alexander Graham Bell invented the telephone, along with Elisha Gray. But Bell was not the inventor of this device, but only the first to patent it. This happened in 1876. On June 11, 2002 the U.S. Congress passed resolution 269, which recognizedby the inventor of the telephone was Antonio Meucci, who called teletrofono, and Alexander Graham Bell. In 1871 Meucci could only by economic difficulties, present a brief description of his invention, but not to formalize the patent before the Patent Office of the United States.
History of invention

Around the year 1857 Antonio Meucci constructed to connect your phone to your bedroom office,located on the second floor, due to rheumatism of esposa.1 however lacked the money to patent his invention, so he presented to a company (Western Union, who promoted the "invention" of Graham Bell) who ignored him, but that neither the materials returned.
In 1876, after discovering that to transmit human voice could only use a direct current, the nationalized Scottish inventor in U.S. AlexanderGraham Bell, built and patented a few hours before his compatriot Elisha Gray's first phone capable of transmitting and receiving human voice in all its quality and timbre. Nor should sideline Thomas Alva Edison, who introduced major improvements in the system, including the microphone is carbon granules.
On June 11, 2002 the U.S. Congress passed resolution 269, which recognized that the inventorof the telephone was Antonio Meucci and Alexander Graham Bell. The resolution, adopted unanimously, U.S. officials estimate that "the life and work of Antonio Meucci should be recognized legally, and that his work in the invention of the telephone should be admitted." According to the text of this resolution, Antonio Meucci installed a rudimentary telecommunications device from the basement ofhis home in Staten Island (New York) and his wife's room, on the first floor.
Evolution of the phone and use
Panasonic Digital Phone.

Since its original conception have been introduced successive improvements in both the handset itself and the methods and systems of network operation.
As regards the telephone apparatus itself, can indicate several things:
The introduction of carbonmicrophone, which considerably increased the power emitted and hence maximum range of the communication.
The device antilocal Luink to avoid hearing disturbance caused by ambient noise of the room where the phone is installed.
Pulse dialing using the so-called dial.
Touchtone dialing.
The introduction or electret microphone electret condenser microphone, used in virtually all modern appliances, whichsignificantly improves the sound quality.
As for the methods and systems of exploitation of the telephone network, can be noted:
The fixed or conventional, that is one that refers to the lines and equipment that handle communication between non-portable telephone terminals, and usually linked together with the central or through metal conductors.
The manual switching telephone exchange tointerconnect through the intervention of an operator / a different phone (Harlond), thereby creating a first network model. First were the central local manuals Battery (phones powered by batteries) and were subsequently manuals Battery power plant (fed from the central cell).
The introduction of automatic switching exchanges, constituted by electromechanical devices of which have existed and stillexist in some cases, various systems: rotary switching system (systems in Spain 7A1, 7A2, 7D, 7BR, AGF), and system crossbar switch (in Spain: Pentaconta Systems 1000, PC32, ARF) and more complex.
The electromechanical automatic switching centers, but controlled by computer. Also called central semielectrónicas (In Spain: 2000 Pentaconta systems, Metaconta, ARE).
The digital switching power...