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 to the edge of the
carrier, or
telecommunications service provider, network. At the edge of the carrier 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)
CO (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., ) provisioned as a single
twisted pair in support of voice communications. However, 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 LEC) and housed in a
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 such as
digital subscriber line (DSL).
Local loop connections can be used to carry a range of services, including:
★ analog voice and signaling used in traditional
POTS
★
Integrated Services Digital Network (ISDN)
★ variants of
Digital Subscriber Line (DSL)
Many owners of local loops are
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
unbundle the local loop, that is, make the local loop available to their competitors.
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:
★ Electric local loop:
PLT and PLC
★ Optical local loop: Fiber Optics services such as
FiOS
★ Satellite local loop:
communications satellite and cosmos Internet connections of
satellite television (
DVB-S)
★ Cable local loop:
Cablemodem
★
Wireless local loop (WLL):
LMDS,
WiMAX,
GPRS,
HSDPA
See also
★
Local loop unbundling
★ The local loop is an example of
outside plant
★
Access network
★
Serving area interface