Note: Many topics at this site are reduced versions of the text in "The Encyclopedia of Networking and Telecommunications." Search results will not be as extensive as a search of the book's CD-ROM.

The local loop is a pair of wires that connect telephone subscribers to the telephone company's CO (central office). The CO is where telephone company switching equipment is located. Some neighborhood buildings are remote switching offices that are connected to a main office via a trunk cable (coaxial or fiber). The two copper wires are individually insulated and twisted around one another to reduce crosstalk.