Subscriber Loop Carrier or Subscriber Line Carrier (SLC - commonly pronounced "slick") refers to equipment providing central office-like telephone

Telephone

The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...

 interface functionality. The SLC Remote Terminal (RT) is typically located in a remote (from the telephone company central office) area with a high density of telephone service such as a residential neighborhood. Two or four T1

Digital Signal 1

Digital signal 1 is a T-carrier signaling scheme devised by Bell Labs. DS1 is a widely used standard in telecommunications in North America and Japan to transmit voice and data between devices. E1 is used in place of T1 outside North America, Japan, and South Korea...

 circuits (depending on the configuration) connect the SLC RT back to the Central Office Terminal (COT) in the case of a Universal Subscriber Loop Carrier (USLC). An Integrated Subscriber Loop Carrier (ISLC) has its T-spans terminating directly in time division switching equipment in the telephone exchange

Telephone exchange

In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...

.

One system serves up to 96 customers. This configuration is more efficient than the alternative of having separate copper pairs between each service termination point

Service termination point

In telecommunication, service termination point is the last point of service rendered by a commercial carrier under applicable tariffs.Usually, the service termination point is on the customer premises and corresponds to the demarcation point. The customer is responsible for equipment and operation...

 (house) and the central office. The term comes from the SLC-96 trademark of Western Electric

Western Electric

Western Electric Company was an American electrical engineering company, the manufacturing arm of AT&T from 1881 to 1995. It was the scene of a number of technological innovations and also some seminal developments in industrial management...

.

A Subscriber Loop Carrier Circuit system manufactured by AT&T

AT&T

AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...

 (now Lucent). SLC-96 has its own version of T1 frame synchronization

Frame synchronization

While receiving a stream of framed data, frame synchronization is the process by which incoming frame alignment signals, i.e., distinctive bit sequences , are identified, i.e., distinguished from data bits, permitting the data bits within the frame to be extracted for decoding or retransmission...

 between it and the CO. This interface is the Telcordia Technologies

Telcordia Technologies

Telcordia Technologies, formerly Bell Communications Research, Inc. or Bellcore, is a telecommunications research and development company based in the United States created as part of the 1982 Modification of Final Judgment that broke up American Telephone & Telegraph...

 (formerly Bellcore) Generic Requirements documents GR-8-CORE or GR-303-CORE interface which are specialized versions of T1 intended to allow transparent transport of analog features such as Caller ID

Caller ID

Caller ID , also called calling line identification or calling number identification or Calling Line Identification Presentation , is a telephone service, available in analog and digital phone systems and most Voice over Internet Protocol applications, that transmits a caller's number to...

, Call Waiting

Call waiting

Call waiting , in telephony, is a feature on some telephone networks. If a calling party places a call to a called party which is otherwise engaged, and the called party has the call waiting feature enabled, the called party is able to suspend the current telephone call and switch to the new...

, etc.

See also

• Pair gain
  Pair gain
  In telephony, pair gain is a method of transmitting multiple POTS signals over the twisted pairs traditionally used for a single traditional subscriber line in telephone systems. Pair gain has the effect of creating additional subscriber lines...
  
  
• Distributed switching
  Distributed switching
  Distributed switching is an architecture in which multiple processor-controlled switching units are distributed. There is often a hierarchy of switching elements, with a centralized host switch and with remote switches located close to concentrations of users....
  
  
• Digital loop carrier
  Digital loop carrier
  A digital loop carrier is a system which uses digital transmission to extend the range of the local loop farther than would be possible using only twisted pair copper wires...
  
  
• Telephone line
  Telephone line
  A telephone line or telephone circuit is a single-user circuit on a telephone communication system...
  
  
• Remote concentrator
  Remote concentrator
  In modern telephony a remote concentrator, Remote Concentrator Unit , or Remote Line Concentrator is the lowest level in the telephone switch hierarchy.Subscribers' analogue telephone/PSTN lines are terminated on concentrators...