Little known fact about phone cables. Have you ever cut open a telephone network cable only to find that in addition to normal copper wires, there is also a string? That string was also in phone lines. While not all cables still have this string, the origin is quite interesting. When Alexander Graham Bell first invented the phone (and thus the wiring between the phones), he included the first known instance of "backwards compatibility" in telecommunications. The string was to allow for the use of a backup communications channel wherein during an outage, a person could connect a tin can to the phone line and continue to make and receive telephone calls, albeit with lesser clarity. Remember when Sprint ran their advertising campaign regarding their call clarity being so good that "you can even hear a pin drop"? They created the first phone network to remove the strings, as the cross-talk from legacy use of the tin cans impacted the call clarity of the copper lines. Their entire infrastructure was created (and retro-fitted as needed) to allow for the removal of this cross-talk and thus they pioneered the first telecommunications network that removed the mostly-obsolete "tin can" string. One of the ultimate causes of the demise of WorldCom (later MCI) was their plan to actually increase the thickness of the string in an attempt to create the first inter-continental phone call using two tin cans and a string. Telecommunications historians believe that the test may actually have been successful except that the amount of tin used in the cans had been lowered and replaced by more aluminum and other metals/alloys. In late 2004, the last string was disconnected within the US telecommunications Central Offices, rendering the use of tin cans for making and receiving calls non-functional.
Posted on: Tue, 02 Jul 2013 02:52:21 +0000