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.

A leased line is a permanent or switched communication circuit between a customer site and a service provider's wide area network, or between two sites owned by a customer (a private line). Leased lines almost always refer to carrier-based TDM circuits, although, in general, any communication link with monthly fee could be called a leased line. This topic discusses carrier TDM circuits.