Evolution_of_Telephones

Evolution of Telephones After the invention of the telephone instrument itself, the second greatest technological advance in the industry may have been the invention of automatic switching called Strowger switches, after Almon Brown Strowger, who invented the system because he didn’t trust his town’s human operators were connecting correct calls. Long-distance telephony was established in small steps. · The first step was the introduction of the long-distance telephone, originally a special highly efficient instrument permanently installed in a telephone company building and used for calling between cities. · The invention at the end of the 19th century of the loading coil (a coil of copper wire wound on an iron core and connected to the cable every mile or so) increased the speaking range to approximately 1,000 miles. · Until the 1910s the long-distance service used repeaters overcome with the invention of the triode vacuum tube, which amplified electrical signals. And until Direct Distance Dialing became available, all long-distance calls still required the assistance of an operator to complete. By adding a three-digit area code and developing telephone, long-distance, invention, service, calls, between, been, because, available, videophones, video, until, switching, strowger, send, provide, popular, phones, phone, machines, introduction, instrument, first, dials, complete, coil, cellular, became, automatic, answering, after, wound, world, wireless, wire