The 1870s saw the arrival one of the world's greatest creations: the telephone. Two inventors, Alexander Graham Bell and Elisha Gray, worked separately on projects to transmit speech across distance, in attempts to improve the existing telegraph systems.
By the time Elisha Gray was ready to patent his product, Alexander Graham Bell had already patented his version. In a battle over the patent rights in court, Alexander Graham Bell won, acquiring the rights to the new communications device that could transmit electronic voice signals over distance.
In fact, communication had been possible over distance with the invention of the telegraph some 30 years before. Bell had been testing methods of communication with electrical signals over the same line. In essence, multiple communication devices could use a single line, unlike the sending and receiving of the telegraph, which required a line of it's own.