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{{Short description|In telephony, the last part of the connection to the customer}}

{{unreferenced|date=February 2008}}

{{more citations needed|date=August 2022}}

[[File:Local Loop.jpg|thumb|Local Loop]]

In [[telephony]], the '''local loop''' (also referred to as a '''subscriber line''') is the physical link or circuit that connects from the [[demarcation point]] of the [[Customer-premises equipment|customer premises]] to the edge of the [[Common carrier|carrier]] or [[telecommunications service provider]]'s network. At the edge of the carrier [[access network]] in a traditional PSTN ([[public switched telephone network]]) scenario, the local loop terminates in a circuit switch housed in an [[ILEC]] (Incumbent Local Exchange Carrier) [[Telephone exchange|CO]] (Central Office).

In [[telephony]], the '''local loop''' (also referred to as athe '''local tail''', '''subscriber line''', or in the aggregate as the [[Last mile (telecommunications)|last mile]]) is the physical link or circuit that connects from the [[demarcation point]] of the [[Customer-premises equipment|customer premises]] to the edge of the [[Commoncommon carrier|carrier]] or [[telecommunications service provider]]'s network.<ref>{{Cite Atweb the|title=What edge of the carrier [[access network]] inis a traditional PSTN ([[public switched telephone network]]) scenario, the local loop? terminates in |url=https://superioressexcommunications.com/faqs/what-is-a-local-loop/ circuit|access-date=2022-08-12 switch|website=Superior housedEssex inCommunications an [[ILEC]] (Incumbent Local Exchange Carrier) [[Telephone exchange|CO]] (Central Office).language=en-US}}</ref>

Traditionally, the local loop was [[Wireline (networking)|wireline]] in nature from customer to central office, specifically in the form of an [[electrical circuit]] (i.e. [[wiktionary:loop|loop]]) provisioned as a single [[twisted pair]] 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 (telephony)|party line]]. Modern implementations may include a [[digital loop carrier]] 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]] (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:

At the edge of the carrier [[access network]] in a traditional public telephone network,<ref>{{Cite web |title=The corDECT Wireless Local Loop: Capacity Predictions |url=https://www.researchgate.net/publication/2888455_The_corDECT_Wireless_Local_Loop_Capacity_Predictions}}</ref> the local loop terminates in a circuit switch housed in an incumbent [[local exchange carrier]] or [[telephone exchange]].

== Infrastructure ==

Traditionally, the local loop was an [[electrical circuit]] in the form of a single pair of conductors from the telephone on the customer's premises to the local [[telephone exchange]]. [[Single-wire earth return]] lines had been used in some countries until the introduction of electric tramways from the 1900s made them unusable.

Historically the first section was often an aerial open-wire line, with several conductors attached to porcelain insulators on cross-arms on "telegraph" poles. Hence [[party line (telephony)|party line]] service was often given to residential customers to minimise the number of local loops required. Usually all these circuits went into aerial or buried cables with a [[twisted pair]] for each local loop nearer the exchange, see [[outside plant]].

Modern implementations may include a [[digital loop carrier]] system segment or [[fiber optic]] transmission system. The local loop may terminate at a circuit switch owned by a [[competitive local exchange carrier]] and housed in a [[point of presence]] (POP), which typically is an incumbent local exchange carrier telephone exchange. A local loop supports voice and/or data communications applications in the following ways:

* analog voice and signaling used in traditional [[Plain old telephone service|POTS]]

* [[Integrated Services Digital Network]] (ISDN)

* variants of [[Digitaldigital Subscribersubscriber Lineline]] (DSL).

The term "local loop" is sometimes used for any "[[Last mile (telecommunications)|last mile]]" connection to the customer, regardless of technology or intended purpose. Hence the phrase "[[wireless local loop]]". Local loop connectionsinterrelations in this sense include:

Many owners of local loops are [[public utility|public utilities]] that hold a [[natural monopoly]].

To prevent the owner from using this natural monopoly to monopolize other fields of trade, some jurisdictions require utilities to [[local loop unbundling|unbundle the local loop]], that is, make the local loop available to their competitors.

*Electric power lines.

The term "local loop" is sometimes used for any "[[last mile]]" connection to the customer, regardless of technology or intended purpose. Hence the phrase "[[wireless local loop]]". Local loop connections in this sense include:

*Cable connections used with television, internet and telephone.

*Electric power line local loop: [[Power Line Communications|PLT]] or PLC

*[[Wireless signals or local loop]] (WLL): [[Local multipoint distribution service|LMDS]], [[WiMAX]], [[GPRS]], [[HSDPA]], [[DECT]]

*Optical local loop: Fiber Optics services such as [[FiOS]]

*Satellite connections for beamed signal.

*Satellite local loop: [[communications satellite]] and cosmos Internet connections of [[satellite television]] ([[Digital Video Broadcasting|DVB]]-S)

*Optical or fiber optics services.

*Cable local loop: [[Cablemodem]]

*[[Wireless local loop]] (WLL): [[LMDS]], [[WiMAX]], [[GPRS]], [[HSDPA]], [[DECT]]

==See also==

* [[Access network]]

* [[ISDN]] (Integrated Services Digital Network)

* [[Local -loop unbundling]]

* [[Metallic Pathpath Facilitiesfacilities]]

*[[Sub-loop unbundling]]

*The local[[Outside loopplant]] is(as an exampleinstance of [[outsidea plant]]local loop)

* [[Serving area interface]]

* [[Telephone line]]

== References ==

{{Reflist}}

{{Authority control}}

[[Category:Telecommunications infrastructure]]

[[Category:Local loop| ]]

[[Category:Local loop| ]]

[[ar:دائرة مغلقة]]

[[Category:Telecommunications infrastructure]]

[[ca:Bucle local]]

[[de:Teilnehmeranschlussleitung]]

[[es:Bucle local]]

[[fr:Boucle locale]]

[[ja:加入者線]]

[[pl:Lokalna pętla abonencka]]

[[vi:Đường dây thuê bao]]