# Local loop

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In telephony, the last part of the connection to the customer

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Local Loop

In [telephony](/source/Telephony), the **local loop** (also referred to as the **local tail**, **subscriber line**, or in the aggregate as the [last mile](/source/Last_mile_(telecommunications))) is the physical link or circuit that connects from the [demarcation point](/source/Demarcation_point) of the [customer premises](/source/Customer-premises_equipment) to the edge of the [common carrier](/source/Common_carrier) or [telecommunications service provider](/source/Telecommunications_service_provider)'s network.[1]

At the edge of the carrier [access network](/source/Access_network) in a traditional public telephone network,[2] the local loop terminates in a circuit switch housed in an incumbent [local exchange carrier](/source/Local_exchange_carrier) or [telephone exchange](/source/Telephone_exchange).

## Infrastructure

Traditionally, the local loop was an [electrical circuit](/source/Electrical_circuit) in the form of a single pair of conductors from the telephone on the customer's premises to the local [telephone exchange](/source/Telephone_exchange). [Single-wire earth return](/source/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](/source/Party_line_(telephony)) 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](/source/Twisted_pair) for each local loop nearer the exchange, see [outside plant](/source/Outside_plant).

Modern implementations may include a [digital loop carrier](/source/Digital_loop_carrier) system segment or [fiber optic](/source/Fiber_optic) transmission system. The local loop may terminate at a circuit switch owned by a [competitive local exchange carrier](/source/Competitive_local_exchange_carrier) and housed in a [point of presence](/source/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](/source/Plain_old_telephone_service)

- [Integrated Services Digital Network](/source/Integrated_Services_Digital_Network) (ISDN)

- variants of [digital subscriber line](/source/Digital_subscriber_line) (DSL).

The term "local loop" is sometimes used for any "[last mile](/source/Last_mile_(telecommunications))" 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): [LMDS](/source/Local_multipoint_distribution_service), [WiMAX](/source/WiMAX), [GPRS](/source/GPRS), [HSDPA](/source/HSDPA), [DECT](/source/DECT)

- Satellite connections for beamed signal.

- Optical or fiber optics services.

## See also

- [Access network](/source/Access_network)

- [ISDN](/source/ISDN) (Integrated Services Digital Network)

- [Local-loop unbundling](/source/Local-loop_unbundling)

- [Metallic path facilities](/source/Metallic_path_facilities)

- [Outside plant](/source/Outside_plant) (as an instance of a local loop)

- [Serving area interface](/source/Serving_area_interface)

- [Telephone line](/source/Telephone_line)

## References

1. **[^](#cite_ref-1)** ["What is a local loop?"](https://superioressexcommunications.com/faqs/what-is-a-local-loop/). *Superior Essex Communications*. Retrieved 2022-08-12.

1. **[^](#cite_ref-2)** ["The corDECT Wireless Local Loop: Capacity Predictions"](https://www.researchgate.net/publication/2888455_The_corDECT_Wireless_Local_Loop_Capacity_Predictions).

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