In telephony

Telephony

In telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....

, the local loop (also referred to as a subscriber line) is the physical link or circuit that connects from the demarcation point

Demarcation point

In telephony, the demarcation point is the point at which the public switched telephone network ends and connects with the customer's on-premises wiring. It is the dividing line which determines who is responsible for installation and maintenance of wiring and equipment -- customer/subscriber, or...

 of the customer premises

Customer-premises equipment

Customer-premises equipment or customer-provided equipment is any terminal and associated equipment located at a subscriber's premises and connected with a carrier's telecommunication channel at the demarcation point...

 to the edge of the carrier

Common carrier

A common carrier in common-law countries is a person or company that transports goods or people for any person or company and that is responsible for any possible loss of the goods during transport...

 or telecommunications service provider

Telecommunications Service Provider

A telecommunications service provider or TSP is a type of communications service provider that has traditionally provided telephone and similar services...

's network. At the edge of the carrier access network

Access network

An access network is that part of a telecommunications network which connects subscribers to their immediate service provider. It is contrasted with the core network, which connects local providers to each other...

 in a traditional PSTN (public switched telephone network

Public switched telephone network

The public switched telephone network is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all inter-connected by...

) scenario, the local loop terminates in a circuit switch housed in an ILEC (Incumbent Local Exchange Carrier) CO

Telephone exchange

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

 (Central Office).

Traditionally, the local loop was wireline in nature from customer to central office, specifically in the form of an electrical circuit (i.e. loop) provisioned as a single twisted pair

Twisted pair

Twisted pair cabling is a type of wiring in which two conductors are twisted together for the purposes of canceling out electromagnetic interference from external sources; for instance, electromagnetic radiation from unshielded twisted pair cables, and crosstalk between neighboring pairs...

 in support of voice communications. Where the number of local loops was restricted, different customers could share the same loop, known as a party line

Party line (telephony)

In twentieth-century telephone systems, a party line is an arrangement in which two or more customers are connected directly to the same local loop. Prior to World War II in the United States, party lines were the primary way residential subscribers acquired local telephone service...

. Modern implementations may include a 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...

 system segment or fiber optic transmission system known as fiber-in-the-loop. The local loop may terminate at a circuit switch owned by a CLEC (Competitive Local Exchange Carrier) and housed in a point of presence

Point of presence

A point of presence is an artificial demarcation point or interface point between communications entities. It may include a meet-me-room.In the US, this term became important during the court-ordered breakup of the Bell Telephone system...

 (POP), which typically is either an ILEC CO or a "carrier hotel". A local loop may be provisioned to support data communications applications, or combined voice and data:

• analog voice and signaling used in traditional POTS
  Plain old telephone service
  Plain old telephone service is the voice-grade telephone service that remains the basic form of residential and small business service connection to the telephone network in many parts of the world....
  
  
• Integrated Services Digital Network
  Integrated Services Digital Network
  Integrated Services Digital Network is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network...
  
   (ISDN)
• variants of Digital Subscriber Line
  Digital Subscriber Line
  Digital subscriber line is a family of technologies that provides digital data transmission over the wires of a local telephone network. DSL originally stood for digital subscriber loop. In telecommunications marketing, the term DSL is widely understood to mean Asymmetric Digital Subscriber Line ,...
  
   (DSL)

Many owners of local loops are public utilities

Public utility

A public utility is an organization that maintains the infrastructure for a public service . Public utilities are subject to forms of public control and regulation ranging from local community-based groups to state-wide government monopolies...

 that hold a natural monopoly

Natural monopoly

A monopoly describes a situation where all sales in a market are undertaken by a single firm. A natural monopoly by contrast is a condition on the cost-technology of an industry whereby it is most efficient for production to be concentrated in a single form...

.
To prevent the owner from using this natural monopoly to monopolize other fields of trade, some jurisdictions require utilities to unbundle the local loop

Local loop unbundling

Local loop unbundling is the regulatory process of allowing multiple telecommunications operators to use connections from the telephone exchange to the customer's premises...

, that is, make the local loop available to their competitors.

The term "local loop" is sometimes used for any "last mile

Last mile

The "last mile" or "last kilometer" is the final leg of delivering connectivity from a communications provider to a customer. The phrase is therefore often used by the telecommunications and cable television industries. The actual distance of this leg may be considerably more than a mile,...

" connection to the customer, regardless of technology or intended purpose. Hence the phrase "wireless local loop

Wireless local loop

Wireless local loop , is a term for the use of a wireless communications link as the "last mile / first mile" connection for delivering plain old telephone service and/or broadband Internet to telecommunications customers....

". Local loop connections in this sense include:

• Electric power line local loop: PLT or PLC
• Optical local loop: Fiber Optics services such as FiOS
  Fíos
  Fíos is one of 17 parishes in Parres, a municipality within the province and autonomous community of Asturias, in northern Spain....
  
  
• Satellite local loop: communications satellite
  Communications satellite
  A communications satellite is an artificial satellite stationed in space for the purpose of telecommunications...
  
   and cosmos Internet connections of satellite television
  Satellite television
  Satellite television is television programming delivered by the means of communications satellite and received by an outdoor antenna, usually a parabolic mirror generally referred to as a satellite dish, and as far as household usage is concerned, a satellite receiver either in the form of an...
  
   (DVB-S)
• Cable local loop: Cablemodem
• Wireless local loop
  Wireless local loop
  Wireless local loop , is a term for the use of a wireless communications link as the "last mile / first mile" connection for delivering plain old telephone service and/or broadband Internet to telecommunications customers....
  
   (WLL): LMDS
  LMDS
  LMDS may refer to:*Los Mismos De Siempre - Abbreviated as LMDS, is fans of La Renga*Local Multipoint Distribution Service, abbreviated as LMDS, being microwave signals to transmit voice, video, and data signals for short distances...
  
  , WiMAX
  WiMAX
  WiMAX is a communication technology for wirelessly delivering high-speed Internet service to large geographical areas. The 2005 WiMAX revision provided bit rates up to 40 Mbit/s with the 2011 update up to 1 Gbit/s for fixed stations...
  
  , GPRS, HSDPA, DECT

See also

• Access network
  Access network
  An access network is that part of a telecommunications network which connects subscribers to their immediate service provider. It is contrasted with the core network, which connects local providers to each other...
  
  
• Local loop unbundling
  Local loop unbundling
  Local loop unbundling is the regulatory process of allowing multiple telecommunications operators to use connections from the telephone exchange to the customer's premises...
  
  
• Metallic Path Facilities
  Metallic Path Facilities
  Metallic Path Facilities are the pair of copper wires that run from a Main Distribution Frame at a telephone company local exchange to the end user's home or business premises.-See also:* Telephone exchange...
  
  
• Sub-loop unbundling
  Sub-loop unbundling
  In the telephony business, Sub-loop unbundling is the process by which a sub-section of part of the local loop is unbundled. In practice this often means the competitor placing a small street cabinet with a DSLAM, next to a telco local copper aggregation cabinet or Serving area interface and using...
  
  
• The local loop is an example of outside plant
  Outside plant
  In telecommunication, the term outside plant has the following meanings:*In civilian telecommunications, outside plant refers to all of the physical cabling and supporting infrastructure , and any associated hardware located between a demarcation point in a switching facility and a demarcation...
  
  
• Serving area interface
  Serving area interface
  The serving area interface or service area interface often called B-box, cross-connect box, cross box, ped , or access point is an outdoor telecommunications cabinet usually mounted on the ground on cable right-of-ways, but sometimes also on telephone poles...
  
  
• Telephone line
  Telephone line
  A telephone line or telephone circuit is a single-user circuit on a telephone communication system...