View source for Engineering:Local loop

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

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

In [[Engineering:Telephony|telephony]], the '''local loop''' (also referred to as the '''local tail''', '''subscriber line''', or in the aggregate as the [[Engineering:Last mile (telecommunications)|last mile]]) is the physical link or circuit that connects from the [[Engineering:Demarcation point|demarcation point]] of the [[Engineering:Customer-premises equipment|customer premises]] to the edge of the [[Common carrier|common carrier]] or telecommunications service provider's network.<ref>{{Cite web |title=What is a local loop? |url=https://superioressexcommunications.com/faqs/what-is-a-local-loop/ |access-date=2022-08-12 |website=Superior Essex Communications |language=en-US}}</ref>

At the edge of the carrier [[Access network|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 [[Engineering:Telephone exchange|telephone exchange]].

== Infrastructure ==
Traditionally, the local loop was an [[Physics:Electrical circuit|electrical circuit]] in the form of a single pair of conductors from the telephone on the customer's premises to the local [[Engineering:Telephone exchange|telephone exchange]]. [[Engineering:Single-wire earth return|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 [[Engineering: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|twisted pair]] for each local loop nearer the exchange, see [[Engineering:Outside plant|outside plant]].

Modern implementations may include a [[Engineering:Digital loop carrier|digital loop carrier]] system segment or fiber optic transmission system. The local loop may terminate at a circuit switch owned by a [[Company:Competitive local exchange carrier|competitive local exchange carrier]] and housed in a [[Engineering:Point of presence|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 POTS
* [[Integrated Services Digital Network]] (ISDN)
* variants of [[Digital subscriber line|digital subscriber line]] (DSL).

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

*Electric power lines. 
*Cable connections used with television, internet and telephone.
*Wireless signals or local loop (WLL): [[Local Multipoint Distribution Service|LMDS]], [[Organization:WiMAX|WiMAX]], GPRS, HSDPA, DECT
*Satellite connections for beamed signal.
*Optical or fiber optics services.

==See also==
* [[Access network]]
* [[Integrated Services Digital Network]]
* [[Engineering:Local-loop unbundling|Local-loop unbundling]]
* [[Metallic path facilities]]
* [[Engineering:Outside plant|Outside plant]] (as an instance of a local loop)
* [[Engineering:Serving area interface|Serving area interface]]
* [[Engineering:Telephone line|Telephone line]]

== References ==
{{Reflist}}


[[Category:Local loop| ]]
[[Category:Telecommunications infrastructure]]

{{Sourceattribution|Local loop}}