DLC also is an abbreviation for Data Link Control.
Digital loop carrier (DLC) is equipment that bundles a number of individual phone line signals into a single multiplexed digital signal for local traffic between a telephone company central office and a business complex or other outlying service area. Typically, up to 24 analog voice calls are combined into a single signal and transmitted over a single copper T-carrier system or E-carrier line, an optical fiber cable, or a wireless connection. In a home, business, or other installation using digital loop carrier, the analog phone lines of individual users are connected to a local DLC box which then converts the analog signals into digital and combines (multiplexes) them into one signal that it sent to the phone company's central office on the single line. At the central office, the combined signal is separated back into the original signals. An estimated 20% of today's telephone users are being served by digital loop carriers.
Digital loop carrier can carry traffic for regular phone calls (plain old telephone service) and Integrated Services Digital Network (ISDN) service. More recently, approaches have been developed for using DLC to handle the higher bandwidth of Digital Subscriber Line (DSL) service.
Digital loop carrier is typically used as an efficient way to provide service to an office building or complex and to extend service to new areas outside the current local loop. DLC is also used to set up telephone service in emergency situations. Customers can easily migrate from a T-1 or E-1 line to fiber optic when it becomes needed and is available.