Local loop

In telecommunications, the local loop is the wiring between the central office ("telephone exchange" in British English) and the customer's premises demarcation point.

The telephony local loop connection is typically a copper twisted pair carrying current from the central office to the customer premises and back again. Individual local loop telephone lines are connected to the local central office or to a remote concentrator.

Local loop connections can be used to carry a range of technologies, including:

• analog voice (for traditional analog telephony).
• ISDN
• DSL:
  • ADSL
  • HDSL
  • SDSL
  • SHDSL
  • VDSL

Last mile

The term "local loop" is also sometimes used loosely for any "last mile" connection to the customer, regardless of technology. Hence the phrase "wireless local loop".

Local loop connections in this sense include:

• Electric local loop: PLT and PLC.
• Satellite local loop: communications satellite and cosmos Internet connections of satellite television.
• Cable local loop: Cablemodem.

Local Loop Unbundling

Local Loop Unbundling (LLU) in the UK is the practice of service providers renting a subscriber's line from British Telecom so that the subscriber may connect to the alternative supplier. It particularly applies to DSL connections. In some cases the local loop is half-unbundled, with BT continuing to provide voice services.

See also

• loop disconnect
• DTMF
• E and M signaling
• middle mile
• last mile