Less Than-Line Voltage

Less Than

Of smaller quantity. Of less importance. The word "less" is always confused with the word "fewer." According to the Oxford American Dictionary, the word "less" is used of things that are measured by amount (for example, eat less butter, use less fuel). Its use with things measured by numbers is regarded as incorrect (for example in "we need less workers;" correct usage is fewer workers.)

Let's Roll

Todd Beamer was a passenger on the doomed Flight 93, taken over on September 11, 2001 by terrorists who intended to use the aircraft as a missile to destroy the White House or the Capitol. He had a telephone line open to an operator in Chicago, who reported hearing him recite the Lord's Prayer before leading a group of heroic passengers to rush the suicidal hijackers. Then Beamer said: "Are you guys ready? Let's roll."

Letter Of Agency

A letter sent by an end user to a telephone company ” local or long distance ” authorizing the end user's equipment vendor to deal on the end user 's behalf with the phone company. A letter of agency is actually a specialized Power of Attorney.

Letter of Intent

See LOI.

Letterbox

When a program or movie which has originally been created for theatre viewing on a 16 by 9 aspect screen is shown on a 4 by 3 aspect television screen there is a black area above and below the picture. This is done to preserve the entire original picture. In short, when you take a Hollywood movie and put it on a TV screen, you can run it with letterboxes and get the whole Hollywood image. Or you can run it full TV screen and lose parts of the left and right hand side of the picture. See Letterboxing. Contrast with Panand-Scan.

Letterboxing

A TV term referring to the technique in which the aspect ratio (width:height) of an original film is preserved by blacking out portions of the TV screen, typically at the top and bottom. No material is cut out, however. You've noticed this when viewing classic films like Ben Hur. Contrast with PAN-AND-SCAN. See Letterbox.

Letters Shift

A physical shift in a teletypewriter, specifically Telex, which enables the printing of alphabetic characters .

Level

1. The power, or amplitude, of a signal measured at a certain point in the circuit. Specifically, the point of measurement is known as a Transmission Level Point (TLP). See also Loss and Pad.

2. Your management position (i.e. "level" in the management structure) in a telephone company. In AT&T and members of the operating Bell telephone companies, employees are identified by their "Levels." At the bottom of the totem pole are crafts people, the installers , the repair people, the trench diggers, etc. They do not have a level. They are often unionized. Management begins one level above the union. They are called first level. They are often called supervisors. Above them are second level managers. Above them are third level managers. They are called district managers. Above them are fourth level managers. They are division managers. Fifth level managers are assistant vice presidents. Sixth level managers are vice presidents. Above vice presidents , levels get fairly vague. Salary is contingent upon level. There are several levels with different salary levels within each level. It is not uncommon for AT&T or for a Bell operating company to have as many as 16 different management levels. At one stage, there was talk about eliminating the fourth level altogether.

3. As wiring got to carry faster and faster data flows, so the quality of wiring has become increasingly important. Thus more and more companies have started specifying cabling standards. Here is a series of standards, which Anixter has promoted:

   • Level 1 VOICE

     Level 1 cables are MADE to meet minimum telecommunication cable requirements.

     Typical uses include analog and digital voice plus low speed data (20 Kbps). Plenum constructions are available in shielded and unshielded designs while PVC constructions are available in shielded designs only.

   • Level 2 ISDN & LOW SPEED DATA Cables support the IBM Type 3 Media requirement. Most uses are defined through the IBM Cabling System guidelines. This specification defines electrical requirements through 1 MHz. These products are available in both plenum and PVC UTP (unshielded twisted pair) constructions. There are no shielded options in Level 2.

   • Level 3 LAN & MEDIUM SPEED DATA

     These products support the ANSI/EIA/TIA-568 Commercial Building Telecommunications Wiring Standard specification horizontal cable (also known as Category 3). This standard defines cable performance through 16 MHz and thus supports high speed LAN applications. Shielded constructions are available.

   • Level 4 EXTENDED DISTANCE LAN

     Level 4 identifies the first 100 ohm premises cables specifically designed for LAN applications. Most UTP LANs require a higher degree of performance than the standard telecommunications design offers. Level 4 cables require performance testing through 20 MHz and provide outstanding crosstalk isolation and attenuation. They are ideal for extended distance 10Base-T and 16 Mbps Token Ring. The specification for Level 4 is referenced from TIA TR41.8.1 Category 4 and NEMA "Low Loss."

   • Level 5 HIGH SPEED LAN 100 OHM

     This level requires the ultimate design for 100 ohm UTP cable. TIA TR4 and the NEMA Premises Wiring Task Force have recently defined this new specification for 100 ohm cable tested through 100 MHz. These cables are intended to be used up to and including 100 Mbps CDDI applications.

   • HIGH SPEED LAN 150 OHM - DGM

     The 150 ohm shielded twisted pair (STP) data grade media is the cornerstone of the IBM Cabling System. In addition to the many IBM applications, this cable is now supported by a consortium of five system vendors for 100 Mbps twisted pair transmission until the ANSI X3T9.5 standard is complete.

   • Level 6

     Increases UTP cable performance by requiring 10dB of ACR (Attentuation-to-Crosstalk Ratio) at 155 MHz. Level 6 cable also must meet more stringent four-pair NEXT (power sum) requirements than must Level 5.

   • Level 7

     Meets at least twice the Category 5 (Level 5) bandwidth requirement. Level 7 UTP achieves 10 dB ACR at 200 MHz, and is power sum-tested to higher NEXT values than is Level 6. Level 7 can support multiple applications at different frequencies with a single cable jacket, and will support Gigabit Ethernet at distances up to 100 meters .

Level 1 Relay

Another name for a repeater. Level 1 indicates that the device operates at the lowest layer (physical layer), as defined by the Open Systems Interconnect (OSI) architecture.

Level 2 Relay

Another name for a bridge. Level 2 indicates that the device operates at the second layer (data link layer), as defined by the Open Systems Interconnect (OSI) architecture.

Level 3 Relay

Another name for a router. Level 3 indicates that the device operates at the third layer (network layer), as defined by the Open Systems Interconnect (OSI) architecture.

Level 7 Relay

Another name for a gateway. Level 7 indicates that the device operates at the seventh layer (application layer) of the Open Systems Interconnect (OSI) architecture.

There are other standards. See also Category of Performance.

Level Playing Field

An area of business competition where all the players enjoy the same rights and privileges. None has special privileges, such as conferred by government regulation. The term has special meaning in the telecom industry where regulation is so pervasive. At one point, the aspiring competitors to the long distance carriers argued for a level playing field. Then when these new competitors got rights and privileges and the older long distance carriers still had the remnants of regulation, the older ones complained. They now wanted a "level playing field." There really is no definition of "level playing field." Everyone defines it the way they want.

Level Mode Interrupt

A method of transmitting an Interrupt Request from a PCMCIA Card to a socket using the IREQ signal. In this mode, the IREQ signal is asserted when the Card initiates an interrupt and is negated when the Host acknowledges to the PC Card that the interrupt has been serviced. The method of acknowledgment is specific to devices on the PCMCIA Card.

Level Sensitive Interrupt

A host system interrupt which causes repeated interrupts as long as the interrupt request signal is in the asserted state and the interrupt request is not disabled. Used in Micro Channel Architecture bus hosts and available in EISA hosts .

Level Sensitive Interrupt Trigger

These adjustable triggers are the key to the operation of the new UART chip, called the 16550. They determine both the amount of data (in bytes) that the UART can receive before generating an interrupt request and the remaining buffer space available to store additional, incoming data. See 16550 and UART.

Leverage

The word "leverage" used as a verb in techno-babble. Really! I'm always hearing companies saying stuff like, "We're going to leverage our blah-blah application off our blah-blah software capabilities...." and trash of a similar nature. It appears they mean, enhance, exploit, capitalize on or some such. Can you enlighten? Francine Brevetti, Business Writer, The Oakland Tribune. Francine, you're right. In the same way, I'm also leveraging my fingers to write this dictionary. It's techno-babble ” big words being substituted for small words plus a big leap in logic. Yuch.

Lexicographer

From the Greek "lexikographos," translating as " grapher of words." In other words, the author of a dictionary. When they want to be cute, my children write down their father's profession on school forms as "lexicographer." None of their classmates or anyone at the school seems to know what the word means. This pleases my children who have inherited their father's perverse sense of humor.

LF

1. Line Feed. ASCII character 10. This character is now identified in the ASCII code set as New Line. See New Line.

2. Low Frequency.

LFIB

Label Forwarding Information Base. A data structure and way of managing forwarding in which destinations and incoming labels are associated with outgoing interfaces and labels.

LFSR

Linear Feedback Shift Register. Mechanism for generating a sequence of binary bits. The register consists of a series of cells that are set by an initialization vector that is, most often, the secret key. The behavior of the register is regulated by a clock. At each clocking instant, the contents of the cells of the register are shifted right by one position, and the exclusive-or of a subset of the cell contents is placed in the leftmost cell . One bit of output usually is derived during this update procedure.

LFSS

Link Failed Signal State.

LG

Line Group.

LGBC

Lightguide Building Cable. Alternative term used for fiber cable in which individual optical fibers are stranded around central members. LGBC cable is used inside a building.

LGC

Line Group Controller.

LGCI

ISDN Line Group Controller.

LGN

An ATM term. Logical Group Node: LGN is a single node that represents the lowest level peer groups in the respective higher level peer group.

LGX

Lightguide Cross-Connect distribution system. A component of fiber optic connecting hardware. This component accommodates 24 to 216 fiber terminations. Also referred to asn n LGX shelf or frame.

LH

Long Haul.

LHMC

Long Haul Mileage Calculation.

Liberty Cabbage

Sauerkraut. During the First World War Americans rechristened sauerkraut "liberty cabbage." In their denunciation of all things German, some patriots stomped dachshunds to death in the streets . During the Second World War the mutts were patriotically renamed "wiener" dogs (a patently American word) and allowed to participate in the war effort.

Liberty Crack

The first known (non-Greek) Trojan Horse targeted for the Palm operating system. It arrived one summer masquerading as an application called "Liberty."

Libor

London Interbank Offered Rate. Some companies pay Libor plus XX% on their bank loans. It's a fancy way of saying you agree to pay a floating interest rate on your loan.

Library

A file that stores related modules of compiled code.

Library of violators

Picture the home page of a typical Web site. Somewhere on the page is a moving graphic ” perhaps an animated GIF ” that screams at you and violates the visual integrity and consistency of the page. Most often, such graphic is designed to deliberately violate the integrity of the page. It is often a paid-for advertisement. And the advertiser wants to draw your attention to his graphic ad. After all, he paid big money for the ad. Such graphic is a called a graphic violator. A collection of graphics violators is called a library.

Licensed bands

There are two types of wireless communications devices. Those that require a licence from the Federal Communications Commission. And those that don't. Those that require a license run in a licensed communications band, a specific frequency. Those that don't require run in unlicensed communications bands can be plugged in and run ” so long as they meet FCC rules for that communications band, i.e. that frequency. The FCC's rules loosely prohibit " harmful interference" of unlicensed devices, but devices that run in an unlicensed band are not guaranteed protection from interference.

LIDB

1. Line Information Data Bases which are being developed by the Regional Bell Operating Companies and all the local phone companies will include such services as Originating Line number Screening, Calling Card Validation, Billing Number Screening, Calling Card Fraud and Public Telephone Check. The LIDB systems contain all valid telephone and calling card numbers in their regions , and have the necessary information to perform billing validation. A national system connecting them all together started working at the beginning of 1992.

2. A Verizon definition. Databases owned individually by Verizon and other entities that provide data such as calling card validation for telephone line number cards issued by Verizon and other entities. An LIDB also contains validation data for collect and third number-billed calls; for example, Billed Number Screening.

LIF

Location Interoperability Forum, formed by Ericsson, Motorola and Nokia in September 2000 with the goal to define, develop and promote common interfaces allowing user appliances and Internet-based applications to obtain location information from wireless networks, independent of positioning methods .

Life After Death

LAD. A satellite term. With the usage of the PMs inside the encoder, the encoders can remain in the scrambled mode for two program epochs' (current and next programs) worth of time per channel after the connection with the UCS (Uplink Control System) has been severed.

Life Cycle

A test performed on a material or configuration to determine the length of time before failure in a controlled, usually accelerated, environment.

Lifeline Service

A minimal telephone service designed for the poor and elderly to assure they can be reached by phone and have a "Lifeline" to the world in case of emergency. Typically, Lifeline Service entitles you to a phone line, a listing in the directory and a minimal number of outgoing local calls, e.g. 10. Some people who are neither poor nor elderly, subscribe to Lifeline Service and use it for incoming calls ” for an answering machine or a computer electronic mail or bulletin boards . There's no difference in the quality of service provided by Lifeline Rates and normal phone lines. The cost of providing life- line service is subsidized at the national level through the settlements pool administered by NECA (National Exchange Carrier Association) under the supervision of the FCC (Federal Communications Commission). NECA Lifeline Assistance Programs include SLC Waiver, which waives either the entire Subscriber Line Charge up to $3.50, or a portion of it; and Link-Up America, which offsets half the initial installation fee, up to $30, and defrays interest expenses. See also NECA, Separations and Settlements, and Universal Service.

LIFO

Last In First Out. A method of organizing queues. See Last In First Out and FIFO.

Liftoff

A term referring to the moment a spacecraft first rises from the ground after its launch. "Five, four, three, two, one, liftoff," the now famous rocketry countdown, was invented by the German director Fritz Lang as a suspense builder for his 1928 science- fiction movie, "Die Frau im Mond," or "The Woman in the Moon," (a.k.a. "By Rocket to the Moon.") A young engineering student, Wernher von Braun, was impressed by the movie, and when he began work on on the V-1 and later the V-2 rocket, used it. Later, after the second World War ended and he and some of his colleagues were brought to the U.S. to continue their work here, the countdown became a familiar part of the space program.

Ligne d'abonne Numerique

French name for DSL. See DSL.

Light

Technically, light is electromagnetic radiation visible to the human eye. The term is also applied to electromagnetic radiation with properties similar to visible light, including the invisible near-infrared "light" (or more technically correct, radiation) that carries signals in most fiber optic communication systems. Light consists of electromagnetic waves ordinarily applied to those having a wave length of from .000075 cm. (the red ray) to .000038 cm. (the violet ray).

Light Amplification of Stimulated Emission of Radiation

LASER. A device which transmits a narrow beam of electromagnetic energy in the visible light spectrum. The light waves are in phase with one another, or coherent , rather than jumbled as in normal light. See Laser.

Light Guide

A light guide is a transmission channel that contains a number of optical fibers packaged together.

Light Emitting Diode

See LED.

Light Pen

A video terminal input device which is a light sensitive stylus connected by a cable to the video terminal. The user brings it to the desired point on the screen surface and presses a button. A light pen is used to select options from a menu on the screen or to draw images by dragging the cursor around the screen on a graphics terminal.

Light Piping

Use of optical fibers to illuminate.

Light Year

The distance that light travels in a pure vacuum (e.g., outer space) during a year. It's a big number. Do the math: 186,000 miles per second x 60 seconds per minute x 60 minutes per hour x 24 hours per day x 365 days per year = 5,865,696,000,000 miles (that's almost six trillion miles). All wave forms in the electromagnetic spectrum propagate at roughly this speed, assuming they are unimpaired by physical matter such as copper wires, earth's atmosphere or glass fibers. Such physical matter not only slows the rate of travel as a result of resistance, but also creates distortion in the signal. See Fiber Optics and Loss.

Lighted Fiber

See Lit Fiber.

Lighting Fiber

See Lit Fiber.

Lightning Arrester

See Lightning Suppressor.

Lightning Rods

Ladies in Europe took to wearing lightning rods on their hats and trailing a ground wire ” a fad that began after Benjamin Franklin published instructions on how to make them in his almanac, Poor Richard Improved, in 1753.

Lightning Suppressor

A device which grounds out surge voltages in order to protect equipment from lightning.

Lightwave Communications

Fiber Optic communications using light to carry information.

Lightwave Transmission

This term now means laser communications systems shot through the air (as opposed to glass fiber). Also called "free space lightwave communications." Typically, a signal is radiated directly from a light transmitter to a receiver less than a mile away. Advantages to lightwave transmission: easy to install, no digging of cables, wide bandwidth, reliable, cheap, no FCC frequency clearance approvals required and the receiving and transmitting equipment occupy little space. Disadvantages: only works for a mile or so and is subject to attenuation (fading) from fog and dust. It's perfect for between downtown buildings , where installing cables is too expensive, too cumbersome, too slow, etc. See Laser.

Lightweight Directory Access Protocol.

See LDAP.

LIJP

An ATM term. Leaf Initiated Joint Parameter: Root screening options and Information Element (IE) instructions carried in SETUP message.

Like New

A term used in the secondary telecom equipment business. It means in excellent condition. Under normal conditions, the like new equipment could pass as new (i.e., not used, but not necessarily in the O.E.M. packaging). See Like New Repair Update.

Like New Repair And Update

LNRU. A term in the industry which repairs telecom equipment. It means all equipment is repaired and updated to the current manufacturer's specifications. New plastic is used to refurbish to a "like new" status. Also added are a new coil cord, line cord and address tray. Included is a full diagnostic test with a burn- in (if required) and an operational system test. Definition courtesy Nitsuko America. See also Repair and Quick Clean and Repair, Update and Refurbish.

LILO

Linux Loader. LILO is a versatile boot loader for Linux. It does not depend on a specific file system. It can boot Linux kernel images from floppy disks and hard disks, and can even boot other operating systems. One of up to sixteen different images can be selected at boot time. Various parameters, such as the root device, can be set independently for each kernel. LILO can even be used as the master boot record.

Lily Livered

The practice of calling cowards "lily-livered" originated in the Middle Ages. Then, it was believed everything was made of four elements: Earth, Air, Fire, and Water. It was also believed that in humans , the Four Contraries: hot, cold, dry, and moist, would combine to form the Four Humors: cholor, blood, melancholy, and phlegm. If someone had demonstrated that they were cowardly, they would be thought of as not having any cholor, or yellow bile, the humor thought to control courage. Since at the time people thought an absence of cholor in the liver would leave it white, the color of the lily, cowards would be called "lily-livered."

LIM

Link Interface Module.

LIM-EMS

The abbreviation for Lotus Intel Microsoft-Expanded Memory Specification. A software technique that allows MS-DOS to access memory beyond one megabyte by mapping the memory into a window in an area that MS-DOS can access. LIM-EMS is one of the greatest techniques for speeding up getting in and out of programs. For example, when my calendar program called Maxi-Calendar is not running, it occupies only 7K of normal RAM and 350K of expanded RAM. When I need it, it swaps itself quickly out of expanded RAM into normal RAM, taking less than half a second. If I didn't have expanded memory, it would take as long as 15 seconds to swap the program onto and off my hard disk, which is the other alternative. LIM stands for Lotus/Intel/Microsoft, the founding organizations that developed the Expanded Memory Specification. AST Research was also part of the driving force behind EMS, though its name doesn't appear in the acronym.

Limelight

People in the public eye are said to be "in the limelight". Invented in 1825, limelight was used in lighthouses and stage lighting by burning a cylinder of lime which produced a brilliant light. In the theater, performers on stage "in the limelight" were seen by the audience to be the center of attention.

Limey

What they call English people in Australia. Captain Cook, who " discovered " Australia for the British, lost 41 of his 98-man crew to scurvy (a deficiency of vitamin C) on his first voyage to the South Pacific in 1768. By 1795, the importance of eating citrus was realized, and lime juice became a standard issue on all British Navy ships. Hence the term "limey" when referring to a Brit.

Limit Order

When you place a "limit order," you instruct your broker or brokerage service to buy or sell this stock at the price I specify.

Limited Distance Modem

LDM. A special purpose conversion device designed to connect two DTEs (data communications devices) over a relatively short distance, typically up to several miles. An LDM is not really a modem since it does not perform a digital-to-analog conversion, but transmits a special type of digital signal to the other LDM on the circuit. Also called a line driver, local dataset or short-haul modem.

Limiter

A circuit which shapes a signal sent through it to conform to certain preset tolerances, used in both audio and video to regulate signal flow and prevent overloading, which would lead to distortion and the introduction of spurious noise.

Limiting Amplifier

Relating to analog signals and their processing. Also refers to the operating range of an amplifier where little or no distortion occurs.

LINCS

Leased Interfaculty National Airspace Communications System.

Line

The word line is confusing. In traditional telecom, a line is an electrical path (two wires) between a phone company central office and a subscriber, usually with an individual phone number that can be used for incoming and outgoing calls. A line, in this definition, is the most common type of loop. In carrier systems, a line is the portion of a transmission system that extends between two terminal locations. The line includes the transmission media and associated line repeaters. A line is also used to indicate the side of a piece of central office equipment that connects to or toward the outside plant. The other side of the equipment is called the drop side. And finally, a line is a family of equipment or apparatus designed to provide a variety of styles, a range of sizes, or a choice of service features. The confusion over the word line starts with an office phone system. Some people believe a line to be the same animal as a trunk ” i.e. the line coming in from the central office to the PBX. Other people think a line is an extension, i.e. the line from the PBX to the phone on the user's desk.

Line Adapter

In communications, a device that converts a signal into a form suitable for transmission over a communications channel. A modem is a specific type of line adapter used to convert the computer's digital signals into analog form so that they can be transmitted over a telephone line.

Line Analyzer

Any device that monitors and displays information about a transmission on a communications channel. A line analyzer is used for troubleshooting and load monitoring.

Line Build Out

Because T-1 circuits require the last span to lose 15-22.5 dB, a selectable out put attenuation is generally required of DTE equipment (typical selections include O.O, 7.5, and 15 dB of loss at 772 KHz).

Line Capacity

A telephone company definition. The maximum number of network access lines that can be working on installed lines at the entity's derived objective percent line fill.

Line Card

1. A plug-in electronic Printed Circuit (PC) card that operates lamps, ringing, holding and other features associated with one or several telephone lines or telephones in a telephone system.

2. A device that transmits and receives optical data and converts optical signals to and from electrical signals. They also transmit multiple data streams to and from other line cards. Line cards plug into switches, cross connects, multiplexers and routers that form the building blocks of optical networks. Each line card connects to a tributary of a long-haul transmission line.

Line Circuit

The sensor in the CO which detects and advises the switching system that one of its subscribers has gone off-hook and wishes to make a call. One line circuit is dedicated to each line of each subscriber.

Line Coding

Line coding can be D4/AMI or B8ZS. See either of these.

Line Concentration Ratio

LCR. Used to determine central office switching equipment quantities and configurations based upon line usage. It is not necessary, nor economical to equip every outside line with a dedicated path through the switch. With the exception of Mother's Day or when George Strait concert tickets go on sale, not every line goes offhook at the same time. The higher ratios have been predominately used in rural areas while the lower, more equipment intensive ratios have been the standard in urban and suburban areas. An LCR of xx:1 indicates there exists 1 predetermined dial tone path for any (xx) lines at a given time; in other words, an LCR of 6:1 means 6 lines would have access to 1 dial tone path through the switch. See LCR for a very detailed explanation.

Line Conditioning

1. A service offered by telephone companies to reduce envelope delay, noise and amplitude distortion. By doing this, you allow for transmission of higher speed data than over a traditional dial-up phone line.

2. The removal by the Incumbent Local Exchange Carrier (ILEC) from the local loop of any devices that may diminish the capability of the loop to deliver high-speed wireline telecommunications capability, including xDSL service. Such devices include bridge taps, low pass filters, and range extenders (e.g., amplifiers and line doublers).

Line Control Unit

LCU. A data communications term used by some vendors for hardware that controls polling and access by remote terminals; most commonly found in minicomputer networks, LCU capability ranges from simple hardware to processor-based devices with a history dating to telegraph networks.

Line Cord

The connecting cord between the phone and the jack in the wall. In North America, it's also known as a mounting cord.

Line Current

A telephone's average off-hook current is about 35 milliamps (mA) or 0.035A. Line current is electrical current measured on an idle telephone line. Typical range is 20 - 100 mA DC, with 40 - 50 mA considered optimum for proper operation of the phone.

Line Discipline

The two most basic elements of a communications protocol are Handshaking and Line Discipline. Line Discipline is the sequence of network operations which actually transmits and receives the data, controls errors in transmission, deals with the sequencing of message sets (e.g., packets, blocks, frames and cells), and provides for confirmation or validation of data received. This definition courtesy of "Communications Systems & Networks," which is Ray Horak's best-selling book. See also Handshaking and Protocol.

Line Disturbance Analyzer

A tool used in analyzing problems in a facility's incoming power. The line disturbance analyzer is connected at the power input to measure and record incoming power, then left in place long enough to gather data typical of the site.

Line Driver

A short haul communications device used when cable lengths between RS-232 devices begin to the alleged 50-foot RS-232 limit. A line driver is a signal converter that conditions the digital signal transmitted by an RS-232 interface to ensure reliable transmission beyond the 50- foot RS-232 limit and often up to several miles; it is a baseband transmission device. Also called baseband modem, limited distance modem, or short-haul modem. See also Limited Distance Modem.

Line Equipment

Equipment in a central office which is there to serve a phone line. That line equipment includes a line relay or equivalent which starts to work when the customer's telephone goes off-hook.

Line Equipment Number

A line equipment number identifies the physical central office line equipment for each subscriber.

Line Error

A Token Ring error reported by any ring station that detects an FCS failure, or some type of protocol code violation in a received frame.

Line Feed

The act of moving a cursor or the head or a printer or telex machine down one line. These days, on the keyboards of most equipment ” Personal Computers, etc. ” there's no single key that says "Line Feed." There's usually a key that's labelled "Enter" or "Return." This key does two functions ” a line feed and a carriage return (i.e. sending the print head or cursor to the left hand side of the carriage or the screen). In many (but not all) programs, a line feed is control J or ASCII character 10. The name for this character has been changed to New Line. See New Line.

Line Finder

The first switching element of a step-by-step phone system which recognizes a calling party is waiting for dial tone to make a call, identifies the party, and connects that party to the switching system so that the processing of the call may begin. Normally line finders serve 100 or 200 subscriber lines.

Line Hit

Electrical interference that causes a hit, that is, a loss or introduction of spurious bits into a data stream.

Line Hold

Provides a winking, blinking flash on the line lamp at every telephone which has the line appearing on it.

Line Information Data Base

See LIDB.

Line Insulation Test

LIT. A test performed from the central office, which measures resistance and voltages on local lines to find faults.

Line Interface Unit

See LIU.

Line Link Frame

LLF. An arrangement that permits a crossbar office to transmit dial pulse information over a line to a PBX for switching Direct Inward Dial (DID) calls to the indicated phone. See Crossbar Switching.

Line Load Control

A control application that limits the number of customers that can obtain dial tone.

Line Lockout

When a phone stays off-hook for longer than a predetermined time, line lockout provides some loud noise and then puts the phone line out of service ” until someone puts the phone back on hook again.

Line Loop Back

LLB. A troubleshooting function of CSU/DSU equipment. The receive pair of a circuit is connected directly back to the transmitter so the line can be tested. If a clear signal is "looped back" to it the line is OK. If there's a problem, it's inside or beyond the receiving equipment.

Line Loss

What the power utility (electricity) business calls theft of service, i.e. when you steal and they can't figure out how to bill.

Line Noise

Spurious signals introduced into a line by static, or other imbalances in the circuit. Line Noise is the most common cause of "Hits" or problems in data calls.

Line Number

The last four digits of a telephone number are called the "line number." A ten-digit telephone number in the U.S., for example, follows the format NXX-NXXXXXX, where N must be a number other than "0" or "1," and X can be any number. The first three digits are the area code, the second three are the central office prefix, and the last four are the line number.

Line Of Sight

Some through the air transmission media ” such as microwave, infrared, and laser ” operate at a frequency which transmit in a perfectly straight line. Or in "line of sight." In other words, the area between a transmitter and a receiver must be clear of obstructions.

Line Pool

A Line Pool is a specific group of lines in certain key systems used for making outside calls. In Northern Telecom's Norstar, three Line Pools give phone access to outside lines without taking up too many Line buttons on each phone instrument.

Line Powered

Telephone equipment that is powered solely by the CO talk battery supplied in a standard phone line.

Line Preference

User selects the line to be used simply by pressing the button associated with that line.

Line Printer

A type of printer which prints an entire line of text at one time. This printer is obviously a high speed printer. It is used, for example, to print TELECONNECT Magazine's monthly mailing list.

Line Protocol

Rules for controlling transmission on a synchronous data transmission line. Includes rules for bidding for the line, for positive and negative acknowledgements, requests for retransmission, and transmitter time-outs.

Line Sharing

The practice by which a CLEC (Competitive Local Exchange Carrier) and an ILEC (Incumbent LEC) share a local loop. It works like this: A DSL provider cuts a deal with an ILEC to run DSL service for Internet access purposes over the same local loop that the ILEC, or voice CLEC uses for voice service. The data CLEC providing the Internet access uses the high-frequency portion (i.e., above 25 KHz) of the local loop for digital packet data transfer, and the ILEC uses the low-frequency portion (i.e., 4 KHz and below) for analog voice. On December 9, 1999, the FCC made line sharing official policy. The FCC order applies only to voice-compatible forms of DSL, such as ADSL and RADSL. HDSL, SDSL and other DSL versions which require use of the entire local loop are not covered by the order, as they are not voice-compatible and, therefore, do not allow the line to be shared. The FCC order also requires the ILECs to provide to a DLC (Digital Loop Carrier) or any other accessible terminal in the outside loop plant. The FCC order further stated that the cost of line sharing arrangements should be on a cost basis. As the ILECs charge themselves zero for such arrangement, the CLEC argument is that they should be charges zero, as well. Several ILECs have agreed to such zero-cost deals. See also ADSL, DLC, HDSL, RADSL, SDSL, and xDSL.

Line Signals

1. In the CCITT sense, equivalent to " supervisory signaling" in Bell network language.

2. In North American colloquial use, any of a wide variety of communications signals as found transmitting a physical transmission medium.

Line Queuing

Dial an outside line (typically a long distance line). It's busy. Your phone system will put you in queue for that line. The queue might involve your waiting a few seconds on hold; or it might involve your hanging up and having the phone system call you back. There are thus two types of Line Queuing ” hold-on and callback queuing.

Line Relay

A telephone company term. Relay in a subscriber's line which operates on the calling-in signal.

Line Ringing

Provides the user with an audible indication of a call on a specific line that appears on his/her telephone.

Line Signals

1. In the CCITT sense, equivalent to "supervisory signaling" in Bell network language.

2. In North American colloquial use, any of a wide variety of communications signals as found transmitting on a physical transmission medium.

Line Side Connection

A carrier term. A local loop, which connects the customer premise to the carrier network. The carrier community uses this term to describe the customer side of the network, regardless of whether it is specifically in the form of a line or a trunk. In this context, the term "trunk" refers to a local loop which connects a network switch (e.g., a central office circuit switch, a frame relay switch or router, or an ATM switch) to a customer switch (e.g., a PBX circuit switch, a frame relay router, or an ATM switch). Also in this context, a "line" connects a network switch to a non-switch (e.g., a telephone set, a computer modem, or a traditional key system). In other words, a trunk connects one switching device to another switching device, while a line connects a non-switching device to another device, which can be in the form of either a switch or a non-switch. Compare with Trunk Side Connection.

Line-Side Termination

An end office switch connection that provides transmission, switching and optional features suitable for customer connection to the public switched network, including loop start supervision, ground start supervision, and signaling for BRI-ISDN service.

Line Speed

The maximum number of bits you can transmit over a line in a certain defined time, say one second.

Line Status Indication

Provides a visual indication on an ECTS (electronic telephone set) telephone of the idle, busy, ringing or held state for each line appearing on the telephone.

Line Switched Ring

A technique for providing redundancy in a SONET network. Line-switched rings use either 2 or 4 fibers per ring. The primary ring transmits in one direction (e.g., clockwise), with the other transmitting in the reverse direction. Through this technique, a failure in a SONET ring will not prevent devices from communicating, as they can transmit and receive at least one direction, assuming that there is no more than 1 break in a fiber. See Path-Switched Ring.

Line Switching

Another term for circuit switching. See Circuit Switching and Switching.

Line Termination

1. Defines the local loop at the telephony company side of a digital connection ” DSL or ISDN. The classic line termination devices is the NTI at the user side of the interface.

2. A Verizon definition. Equipment that terminates a BRI or Centrex BRI digital subscriber line on the network side of the network to the end user (or CLEC) interface. Alternatively, electronics at the ISDN network side of the user-network interface that complement the electronics equipment.

Line Transfers

A telephone company definition. Line transfers consist of physically removing a customer line from one line equipment and moving it to another. Line transfers are used as an important corrective tool to improve load balance.

Line Turnaround Time

The delay in a circuit as the direction of communications changes, usually in half duplex communications. When one side of the communications stops sending, there is a delay before the other party stars sending in return. This is the Line Turnaround delay.

Line Up

Plant technician colloquialism for testing and adjusting transmission performance of a circuit to specified levels and losses at various points along the circuit.

Line Voltage

Voltage measured on a telephone circuit; typically 48 volts DC when phone is idle. Voltage may be lower at great distance from the central office, or when carrier equipment is used to multiplex several phone lines on one pair of wires. Line voltage on PBX systems is typically 24 volts .