User talk:Abhi 02M

'''TELEPHONY SYSTEM  History& Development'Italic text''

Telephone systems were developed for conveying human speech information & data transportation.

Using modems that operate within the same frequency band as human voice.

Anyone who uses a telephone on a telephone circuit is part of a global communications network - Public Telephone Network (PTN)  Telephone interfacing set & Subscriber Loop''' The Subscriber Loop Plain Old Telephone Service (POTS) The simplest form Straightforward Subscribers accessing the public telephone network through a pair of wires – Local subscriber loop @ local loop Local loop unshielded twisted pair transmission line consisting of 2 insulated conductors twisted together. Insulating material : Polyethylene plastic coating Conductor : Pair of 116 t0 26 gauge copper wire