The United States Patent Office issued patent #174,465 to Alexander Graham Bell on March 7, 1876, for his device that could transmit speech electrically: the telephone. On March 10, Mr. Bell spoke the first intelligible words into the device: "Mr. Watson, come here, I want to see you."
Bell and his assistant, Thomas Watson, began their experiments approximately four years prior with attempts to enhance the telegraph, which transmitted information by an intermittent current. They were looking for a way to send multiple messages simultaneously using a harmonic approach where continuous signals were sent in different pitches. What they wound up discovering instead was a way to talk with electricity.