Chapter 6 : Public Switched Telephone Network (PSTN) (Page One)

Of the many wonderful scientific discoveries and inventions which have made the nineteenth century remarkable, certainly none is of more popular interest than the simple little piece of apparatus known as Bell's articulating telephone. By this instrument it becomes possible to transmit ideas between far-distant places, not in the form of signs afterwards to be deciphered, but as actual articulations, an echo of those produced by the human voice at the point of transmission. Wonders of the Uni