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Local loop

Local loop - Wikipedia
Local loop - Wikipedia

In telephony, the local loop (also referred to as the local tail, subscriber line, or in the aggregate as the last mile) is the physical link or circuit that connects from the demarcation point of the customer premises to the edge of the common carrier or telecommunications service provider's network. At the edge of the carrier access network in a traditional public telephone network, the local loop terminates in a circuit switch housed in an incumbent local exchange carrier or telephone exchange. 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 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 POTS Integrated Services Digital Network (ISDN) variants of digital subscriber line (DSL). The term "local loop" is sometimes used for any "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.

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Related concepts (11)
Telephone exchange
A telephone exchange, telephone switch, or central office is a telecommunications system used in the public switched telephone network (PSTN) or in large enterprises. It interconnects telephone subscriber lines or virtual circuits of digital systems to establish telephone calls between subscribers. In historical perspective, telecommunication terms have been used with different semantics over time. The term telephone exchange is often used synonymously with central office, a Bell System term.
Local exchange carrier
Local exchange carrier (LEC) is a regulatory term in telecommunications for the local telephone company. In the United States, wireline telephone companies are divided into two large categories: long-distance (interexchange carrier, or IXCs) and local (local exchange carrier, or LECs). This structure is a result of 1984 divestiture of then-regulated monopoly carrier American Telephone & Telegraph. Local telephone companies at the time of the divestiture are also known as Incumbent Local Exchange Carriers (ILEC).
Telephone company
A telephone company is a kind of communications service provider (CSP), more precisely a telecommunications service provider (TSP), that provides telecommunications services such as telephony and data communications access. Many telephone companies were at one time government agencies or privately owned but state-regulated monopolies. The government agencies are often referred to, primarily in Europe, as PTTs (postal, telegraph and telephone services). Telephone companies are common carriers, and in the United States are also called local exchange carriers.
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