Serving area interface

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SAI in New Jersey VZ SAI workers Secaucus jeh.JPG
SAI in New Jersey

The serving area interface or service area interface (SAI) is an outdoor enclosure or metal box that allows access to telecommunications wiring.

Contents

Alternate names

Function

The SAI provides the termination of individual twisted pairs of a telephony local loop for onward connection back to the nearest telephone exchange (US: "central office" (CO)) or remote switch, or first to transmission equipment such as a subscriber loop carrier multiplexer and then to the exchange main distribution frame (MDF).

Point of appearance is a generic term for any point in a telephone/data circuit from which a technician can test or pull stats. Some appearances are virtual, such as a Digital cross connect system computer terminal. Others are physical, like a punch down COSMIC frame where a technician can place a test set, or a heat coil socket. In the outside plant there is an appearance at the cross box, pedestal, and network interface. The ultimate appearance is the telephone or other customer premises equipment (CPE).

Twisted pair wiring in which two conductors of a circuit are twisted together to improve electromagnetic compatibility

Twisted pair cabling is a type of wiring in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility. Compared to a single conductor or an untwisted balanced pair, a twisted pair reduces electromagnetic radiation from the pair and crosstalk between neighboring pairs and improves rejection of external electromagnetic interference. It was invented by Alexander Graham Bell.

In telephony, the local loop 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.

In the United Kingdom, the components from the PCP onwards to the customer are known as "D-side" (distribution side), and from the PCP back to the MDF as the "E-side" (exchange side). In the United States, the connection back to the MDF is known as the F2 (secondary distribution cable) and/or the F1 (main feeder cable) pairs.

In a UK telephone line, the term D-side or distribution side refers at any point on a local loop connection between a customer's premises and a telephone exchange to the wires leaving into the direction of the customer. Conversely, E-side is the exchange side of a telephone line, that is the wires leaving any connection point into the direction of the telephone exchange.

SAIs are used in suburban and low-density urban areas, serving some of the same purposes that manholes do in high-density urban areas. Besides a cross connect point, they sometimes contain a DSLAM or more rarely a remote concentrator or both.

Remote concentrator

In modern telephony a remote concentrator, remote concentrator unit (RCU), or remote line concentrator (RLC) is a concentrator at the lowest level in the telephone switch hierarchy.

See also

Demarcation point Boundary of a private and public network

In telephony, the demarcation point is the point at which the public switched telephone network ends and connects with the customer's on-premises wiring. It is the dividing line which determines who is responsible for installation and maintenance of wiring and equipment—customer/subscriber, or telephone company/provider. The demarcation point varies between countries and has changed over time.

Fiber to the telecom enclosure

Fiber to the telecom enclosure (FTTTE), also sometimes called fiber to the zone (FTTZ), or fibre to the cabinet (FTTC) in the UK is a standards-compliant structured cabling system architecture that extends the optical fiber backbone network from the equipment room, through the telecom room, and directly to a telecommunications enclosure (TE) installed in a common space to serve a number of users in a work area.

In the telephony business, sub-loop unbundling (SLU) is a type of unbundled access whereby a sub-section of the local loop is unbundled. In practice this often means the competitor placing a small street cabinet with a DSLAM, next to a telco local copper aggregation cabinet or serving area interface and using a 'tie cable' to connect to the last part of the local loop into customers' homes.

Related Research Articles

An intermediate distribution frame (IDF) is a distribution frame in a central office or customer premises, which cross-connects the user cable media to individual user line circuits and may serve as a distribution point for multipair cables from the main distribution frame (MDF) or combined distribution frame (CDF) to individual cables connected to equipment in areas remote from these frames.

Main distribution frame

In telephony, a main distribution frame is a signal distribution frame for connecting equipment to cables and subscriber carrier equipment.

Network interface device device that serves as the demarcation point between the carriers local loop and the customers premises wiring

In telecommunications, a network interface device is a device that serves as the demarcation point between the carrier's local loop and the customer's premises wiring. Outdoor telephone NIDs also provide the subscriber with access to the station wiring and serve as a convenient test point for verification of loop integrity and of the subscriber’s inside wiring.

Outside plant

In telecommunication, the term outside plant has the following meanings:

Digital subscriber line access multiplexer Network equipment

A digital subscriber line access multiplexer is a network device, often located in telephone exchanges, that connects multiple customer digital subscriber line (DSL) interfaces to a high-speed digital communications channel using multiplexing techniques.

Registered jack electrical connector

A registered jack (RJ) is a standardized telecommunication network interface for connecting voice and data equipment to a service provided by a local exchange carrier or long distance carrier. Registration interfaces were first defined in the Universal Service Ordering Code (USOC) system of the Bell System in the United States for complying with the registration program for customer-supplied telephone equipment mandated by the Federal Communications Commission (FCC) in the 1970s. They were subsequently codified in title 47 of the Code of Federal Regulations Part 68.

Distribution frame

In telecommunications, a distribution frame is a passive device which terminates cables, allowing arbitrary interconnections to be made.

Structured cabling telecommunications cabling infrastructure

In telecommunications, structured cabling is building or campus cabling infrastructure that consists of a number of standardized smaller elements called subsystems.

A subscriber loop carrier or subscriber line carrier (SLC) provides telephone exchange-like telephone interface functionality. An SLC remote terminal is typically located in an area with a high density of telephone subscribers, such as a residential neighborhood, that is remote from the telephone company's central office. Two or four T1 circuits connect the SLC remote terminal to the central office terminal (COT), in the case of a universal subscriber loop carrier (USLC). An integrated subscriber loop carrier (ISLC) has its T-spans terminating directly in time division switching equipment in the telephone exchange.

Fiber to the <i>x</i> any broadband network architecture using optical fiber to provide all or part of the local loop used for last mile telecommunications

Fiber to the x (FTTX) or fiber in the loop is a generic term for any broadband network architecture using optical fiber to provide all or part of the local loop used for last mile telecommunications. As fiber optic cables are able to carry much more data than copper cables, especially over long distances, copper telephone networks built in the 20th century are being replaced by fiber.

Junction box

An electrical junction box is an enclosure housing electrical connections, to protect the connections and provide a safety barrier.

Openreach is a functional division of telecommunications company BT plc, that owns and maintains the telephone wires, ducts, cabinets and exchanges that connect nearly all homes and businesses in the United Kingdom to the national broadband and telephone network.

Automated main distribution frame (AMDF),, a technology to provide connectivity between subscriber – and office equipment lines in a telephone exchange main distribution frame (MDF).

British telephone socket

British telephone sockets were introduced in their current plug and socket form on 19 November 1981 by British Telecom to allow subscribers to connect their own telephones. The connectors are specified in British Standard BS 6312. Electrical characteristics of the telephone interface are specified by individual network operators, e.g. in British Telecom's SIN 351. Electrical characteristics required of British telephones used to be specified in BS 6305.

References

  1. 1 2 "Multimedia Telecommunications" (BT Telecommunications Series), B. Whyte (Ed.), Springer 1997