A silly abbreviation for First Come First Served . See FIFO (First In, First Out).


Facility Circuit ID.


Abbreviation for Function. This button enables your cellular phone or fax machine or other telecom device to access special features, like switching from one cellular phone company to another. See also Dual NAM.


Fully programmable classes of service that control user (Feature Class of Service) access to mailbox features, operations and options. Feature Classes of Service (FCOS) are entirely independent of Limits Classes of Service (LCOS).


See Fiber Control Office Terminal.


  1. Frame Check Sequence. Any mathematical formula which derives a numeric value based on the bit pattern of a transmitted block of information and uses that value at the receiving end to determine the existence of any transmission errors. In bit-oriented protocols, a frame check sequence is typically a 16-bit field that contains transmission error checking information, usually appended to the end of the frame. See Frame Check Error and Frame Check Sequence.

  2. Federation of Communications Services.

  3. An MCI term for Fraud Control System.

FCS Error

A Frame Check Sequence error occurs when a packet is involved in a collision or is corrupted by noise.


Fibre Channel Systems Initiative formed by Hewlett-Packard, IBM and Sun in 1993.


See Floor Distributor.


Food and Drug Administration. Organization responsible for laser safety.


Forward Digital Control CHannel. A digital cellular term defined by IS-136, which addresses cellular standards for networks employing TDMA (Time Division Multiple Access). The FDCCH includes all signaling and control information passed downstream from the cell site to the user terminal equipment. The FDCCH acts in conjunction with the RDCCH (Reverse Digital Control CHannel), which includes all such information sent upstream from the user terminal equipment to the cell site. The FDCCH includes the BCCH, SCF and SPACH. See also BCCH, IS-136, SCF, SPACH and TDMA.


  1. Floppy Disk Drive. A Hard Disk Drive is a HDD.

  2. Frequency Division Duplex. A method used to achieve full duplex communications in wireless systems. The principle is that forward and reverse directions each use a separate and equally large frequency band . FDD is appropriate for symmetrical services such as voice and bidirectional data transfers. See also Long Range Ethernet and TDD.


Fiber Distributed Data Interface. FDDI is an ANSI standard (X3T12) for a 100-Mbps fiber optic LAN employing a dual counter-rotating ring topology, using a token-passing technique for media access control, and using the 4B5B encoding scheme for Clock/Data Recovery (CDR). FDDI rings may use up to 200 km of optical fiber, or may employ twisted copper pairs for short hops, including terminal connections. FDDI generally is deployed in backbone applications, where it is used to join file servers, routers, switches, hubs, and other significant computing resources. The theoretical limit of Ethernet, measured in 64 byte packets, is 14,800 packets per second (pps). By comparison, Token Ring is 30,000 and FDDI is 170,000 pps. See also 4B5B, CDDI, FDDI TERMS, and FDDI-II.

FDDI Follow-On LAN

A faster FDDI. Said to operate at up to 2.4 gigabits per second.

FDDI Terms

DAC Dual Attachment Concentrator

DAS Dual Attachment Station

ECF Echo Frames

ESF Extended Service Frames

LER Link Error Rate

LLC Logical Link Control

MAC Media Access Control

MIC Media Interface Connector

NIF Neighborhood Information Frame

NSA Next Station Addressing

PDU Protocol Data Unit

PHY Physical Protocol

PMD Physical Media Department

PMF Parameter Management Frames

RAF Resource Allocation Frames

RDF Request Denied Frames

SAC Single Attachment Concentrator

SAS Single Attachment Station

SDU Service Data Unit

SIF Station Information Frames

SMT Station Management

SRF Status Report Frame

THT Token Holding Timer

TRT Token Rotation Timer

TTRT Target Token Rotation Timer

TVX Valid Transmission Timer

UNA Upstream Neighbor Address


Fiber Distributed Data Interface-II is a recently standardized enhancement to FDDI. It still runs at 100 million bits per second on fiber or on twisted copper pairs, but in addition to transporting conventional packet data like other LANs, FDDI-II allows portions of the 100 Mbps bandwidth to carry low delay, constant bit rate, isochronous data like 64 Kbps telephone channels. This means the same LAN that carries computer packet data can carry live voice or live video calls. Some additional terms used with FDDI-II are: I-MAC which stands for Isochronous Media Access Control; P-MAC which stands for Packet Media Access Control; and WBC which stands for Wide Band Channel. See FDDI, FDDI Terms, Isochronous and Isoethernet.


Facilities Data Link. A T-1 term, specifically relating to Extended SuperFrame (ESF). ESF extends the superframe from 12 to 24 consecutive and repetitive frames of information. The framing overhead of 8 Kbps in previous T-1 versions was used exclusively for purposes of synchronization. ESF takes advantage of newer channel banks and multiplexers which can accomplish this process of synchronization using only 2 Kbps of the framing bits, with the framing bit of only every fourth frame being used for this purpose. As a result, 6 Kbps is freed up for other purposes. This allows 2 Kbps to be used for continuous error checking using a CRC-6 (Cyclic Redundancy Check-6), and 4 Kbps to be used for a FDL which supports the communication of various network information in the form of in-service monitoring and diagnostics. ESF, through the FDL, supports non- intrusive signaling and control, thereby offering the user "clear channel" communications of a full 64 Kbps per channel, rather than the 56 Kbps offered through older versions as a result of "bit robbing." See also ESF and T-1. The FDL is embedded in the framing bits, using half the bits or 4000 bit/s. It is over this channel that two schemes operate:

  1. In the original Bell System scheme, the repair station in the CO queries the CSU at the customer site, which responds with error statistics for the last 24 hours (in 15-min increments ). The repairman uses this info to diagnose line condition.

  2. The more modern ANSI method has the CSU broadcast the error statistics for the last three seconds, every second (with overlap). Automatic monitoring equipment in the CO can tell when the line is going bad. Both systems can co-exist and operate on the same link, but that's unlikely in reality.


Frequency Division Multiplexing. A technique in which the available transmission bandwidth of a circuit is divided by frequency into narrower bands, each used for a separate voice or data transmission channel. This means you can carry many conversations on one circuit. The conversations are separated by "guard channels." At one point, FDM was the most used method of multiplexing long haul conversations when they were transmitted in analog microwave signals. No more. Fiber optic transmission (today's preferred method) uses TDM ” Time Division Multiplexing.


Frequency Division Multiple Access. One of several technologies used to separate multiple transmissions over a finite frequency allocation. FDMA refers to the method of allocating a discrete amount of frequency bandwidth to each user to permit many simultaneous conversations. In cellular telephony, for example, each caller occupies approximately 25 kHz of frequency spectrum. The cellular telephone frequency band, allocated from 824 MHz to 849 MHz and 869 MHz, consists of 416 total channels, or frequency slots, available for conversations. Within each cell, approximately 48 channels are available for mobile users. Different channels are allocated for neighboring cell sites, allowing for re-use of frequencies with a minimum of interference. This technique of assigning individual frequency slots, and re-using these frequency slots throughout the system, is known as FDMA. See CDMA, TDMA.


Fiber Optic Distribution Panel.


Frequency Division Switching. Seldom used for voice switching. Primarily used for radio and TV broadcasting.


See Full Duplex.


Extended Framing ("F sub E"). An old name for ESF, also known as Extended SuperFrame, a T-1 carrier framing format that provides a 64 Kbps clear channel, error checking, 16 state signaling and some other nice data transmission features.

FE D4 Superframe Extended

Another designation for AT&T's ESF (Extended SuperFrame).


An imaging term. An effect in which the edges of a pasted selection or paint tool fade progressively at the edges for a seamless blend with the background.

Feather in your cap

The term came from the American Indian tradition of obtaining feathers for headdresses. Birds were captured, some feathers plucked, and the birds were released. Each feather represented an act of bravery. The fashion of decorating hats with feathers declined in the twentieth century because too many birds were being slaughtered for their feathers.


A pound of feathers weighs more than a pound of gold. Feathers are weighed by "avoirdupois" weight measure, which has 16 ounces to a pound, while gold is weighed in "troy" measure, which only has 12 ounces to a pound .

Feature/Function Access Code

A code in the form *XX or XX and currently used by end users for control of and access to custom calling services (such as activation and deactivation of call forwarding and making changes to speed calling lists). Such features might also include "dial the last number that called me," "dial the last number I just called," "conference two phone conversations together."


When a vendor can't tell you in simple words what his equipment does, he says his equipment (or software) is "feature-rich."


A feature is one of the many tasks a piece of equipment can accomplish. In the old days of selling telephone systems, there used to a be an expression among sales- people that "The one with the biggest list of features wins." As a result many salespeople used to inflate their list of features by calling one feature by many names . Do not confuse a feature with the word "function," which is a much higher level word. The function of a telephone system is to be a phone system. While a phone system can have many features, it can have only one function.

Feature Boards

Modular system cards that perform specific functionality - video or modem cards, for example.

Feature Buttons

Think of a feature button on a telephone as a collection of numbers stored in a bin. When you hit the button, the bin quickly disgorges all the numbers one after another. Feature buttons are fast ways of doing things. You have a feature button labelled "Conference." Hit the button, set up a conference call. Without a feature button, you'd probably have to hit the switch hook and some numbers on your touchtone pad. In computer terms, a feature button on a phone is the same as a macro ” an easy way of doing something. On most phones with feature buttons, the feature buttons are "programmable." This means you can assign different features to different buttons, i.e. the ones you want. For example, I always assign "Last Number Redial," "Saved Number Redial" and "Conference Call" to the buttons of any phone I'm programming. Some phones have many feature buttons. Some don't.

Feature Cartridge

A replaceable software cartridge containing software features. The Feature Cartridge is inserted into the central cabinet, or Key Service Unit (if it's a key system). Several small phone systems (under 100 lines) use cartridges to upgrade their software. The manufacturers find cartridges are cheaper than equipping their phone systems with a floppy drive and the associated electronics.

Feature Code

This is a number that is used to activate a particular feature on a phone system.

Feature Creep

Occupational hazard The enemy of the good is the better. A term to show how features tend to get added to telecom equipment as time passes and new models appear. The term "feature creep" makes no judgments about whether the new features are actually useful. In book called "Startup; A Silicon Valley Adventure Story," Jerry Kaplan, the author, describes "Feature creep as "the irresistible temptation for engineers to load a product down with their favorite special features."

Feature Function Testing

Feature/function testing is designed to assure that everything a system is supposed to do is done correctly, e.g. calls are switched to the correct destination, messages are left and deleted, billing records collected accurately, and so on. Feature/function testing is the most detailed portion of the test process. The people who perform functional testing must be extremely detail oriented and have the discipline to test every feature to their written functional requirement. No function of the system should be overlooked. Definition courtesy Steve Gladstone, from his book "Testing Computer Telephony Systems."

Feature Group A, B, C, D

FGA, FGB, FGC, FGD, are four separate switching arrangements available from local exchange carrier (LEC) end central offices to interex- change (long distance) carriers . These switching arrangements allow the LECs' end-users to make toll calls via their favorite long distance carrier. Feature groups are described in a tariff filed by the National Exchange Carrier Association with the FCC. The feature group used by each IX (IntereXchange, also called long distance) carrier together with any special access surcharge determines the service they can provide their customers and the carrier common line access fee they will pay to the local exchange carrier involved. The most common Feature Group now is D. See the next four definitions. See Feature Group A, Feature Group B, Feature Group C, Feature Group D.

Feature Group A

Offers access to the local exchange carrier's network through a subscriber-type line connection rather than a trunk. It is a continuation of the ENFIA arrangement used in the early days of OCCs, until equal access using an access tandem central office is available. Remember, without equal access the IX carrier had to require its customers to dial a local number to reach their long distance facilities, then dial an identification number, then dial long distance numbers of the called party desired. This service handicap, compared to AT&T's superior connections, qualifies the OCC for a discount off the FGA rate until access is equal. The IX carrier is billed by the LEC based upon actual monthly use rather than the ENFIA method of projected "minutes of use" rate.

Feature Group B

Is similar to FGA, but provides a higher quality trunk line connection from end CO to the IX carrier's facilities, instead of the subscriber-type line. The IX customer can originate a call from anywhere within the LATA, while FGA requires customers to initiate the call from within the local exchange of the exchange carrier connecting to the IXC. FGB billings to the IX are on a flat usage basis, and a discount is applicable . To access a long distance carrier with Feature Group B capability, you dial 950-XXXX (XXXX is the Carrier Identification Code, or CIC), and then 1+ the number. Feature Group D is better. See also 950-XXXX and CIC.

Feature Group C

Is the traditional toll service arrangement offered by LECs to AT&T prior to breakup of the Bell System. Quality is superior, and the service includes automatic number identification of the calling party, answerback, and disconnection supervision, and the subscribers can use either a dial or touchtone pad. This FGC service is offered only to AT&T without a discount.

Feature Group D

FGD. The class of service associated with equal access arrangements. All facilities based IXCs (IntereXchange Carriers) and resellers of significance pay extra for Feature Group D terminations (connections), which is a trunk-side connection provided by the ILECs (Incumbent Local Exchange Carriers). Feature Group D is required for equal access, which allows phone users in the United States to pick up the telephone and dial 1+ to place a long distance call, with the call being handled by the IXC they have preselected. Without FGD, the user must first dial a 7- or 10-digit number, a calling card number and PIN number, and then the desired telephone number. FGD also is required for an end user organization desiring ANI (Automatic Number Identification) information. Feature Group D also lets you dial around your preselected IXC to use another of your choice by dialing 101XXXX. See also 1+, 101XXXX, ANI, Equal Access, ILEC and IXC.

Feature Keys

Same as FEATURE BUTTONS. A key is to a telephone man what a switch is to an electrical man.

Feature Phone

A generic name for a telephone that has extra features (often speed dial buttons) designed to simplify and speed making and receiving phone calls.

Feature Transparency

A PBX to PBX signaling exchange which trigger additional PBX services after a connection have been established, e.g. to display calling party name and number, call back when busy, call forwarding, executive override etc. Feature transparency is implemented by all major PBX vendors in their proprietory signaling systems and it will work between like phone systems made by the same manufacturer (though I personally wouldn't trust it, unless I saw it working and I got a guarantee in writing with a penalty). It is also supported (to an extent) in such open signaling systems as Q.SIG and DPNSS.

Feature/Function Testing

Feature/function testing is designed to assure that everything a system is supposed to do is done correctly, e.g. calls are switched to the correct destination, messages are left and deleted, billing records collected accurately, and so on. Feature/function testing is the most detailed portion of the test process. The people who perform functional testing must be extremely detail oriented and have the discipline to test every feature to their written functional requirement. No function of the system should be overlooked. Definition courtesy Steve Gladstone, from his book "Testing Computer Telephony Systems."


Far End Block Error. A maintenance signal transmitted in the PHY (Physical) overhead, indicating that a bit error(s) has been detected at the PHY layer at the far end of the link. The PHY is the Physical Layer (Layer 1) of the OSI Reference Model, and refers to the transmission facility, such as T-3 or SONET link. A block is a data block, such as a T-3 frame or an OC-1 SONET frame. The "far end" is the end of the physical circuit farthest from the edge of the network, i.e., the premises end. Errors are detected through an error detection algorithm such as block parity. When the Circuit Terminating Equipment (CTE), such as an ATM switch or a router, at the customer premises detects an error in a data block in a downstream transmission, it sends the CTE at the near end an error message. Based on the FEBE, both CTE increment the error count by one, in order to monitor and maintain a record of the bit error performance of the link. That information is used by a network management system to generate alarms and historical reports of network performance. NEBE (Near End Block Error) is essentially the same thing, only at the "near end," i.e., the network end, of the link.


On the Roman holiday Lupercal (February 14) goats were sacrificed and the blood was smeared on two specially chosen youths. The youths would then run all around Rome with strips of goat hide in their hands. Women would strive to be beaten with these strips , known as februa (purifiers). Hence, February gets its name as the month of purification.


  1. Forward Error Correction. A technique used by a receiver for correcting errors incurred in transmission over a communications channel without requiring retransmission of any information by the transmitter. Typically involves a convolution of the transmitter using a common algorithm and embedding sufficient redundant information in the data block to allow the receiver to correct. While this technique is processor- intensive , it improves the efficiency with which the network is used. See Forward Error Correction.

  2. Forwarding Equivalence Class. A MPLS (Multiprotocol Label Switching) term. See MPLS.


Forward Explicit Congestion Notification. A Frame Relay term. This bit contained within the Address Field notifies the receiving device that the network is experiencing congestion. Thereby, the target device is advised that frames may be delayed, discarded, or damaged in transit. It is the responsibility of the target device to adjust to that condition. In conjunction with BECN, devices in both the forward and backward directions are advised. See BECN.


  1. Field Emission Display. A new way of making TV and computer screen displays. FED screens are flat and potentially cheap. Like conventional glass screens, they emit light. LCDs, by comparison, don't. A typical FED screen packs millions of tiny individual emitters between two ultra -thin glass layers . Each emitter fires electrons simultaneously across a minuscule vacuum gap onto a phosphor coating very much like a CRT's. See also Field Emission Displays.

  2. Fire Emitting Diode. Diodes not installed properly can become SEDs (Smoke Emitting Diodes), which then can become FEDs. See also Diode.


A system of standards numbered FED-STD-1001 to 1008 which set modulation specifications for data transmission.

Federal Aviation Administration

FAA. The federal regulatory agency responsible for air safety. Establishes antenna tower marking requirements.

Federal Communications Commission

FCC. The federal organization in Washington D.C. set up by the Communications Act of 1934. It has the authority to regulate all interstate (but not intrastate ) communications originating in the United States. The FCC is the U.S. federal regulatory agency responsible for the regulation of interstate and international communications by radio, television, wire, satellite and cable. Established by the Communications Act of 1934, it is responsible directly to Congress and is directed by five Commissioners appointed by the President and confirmed by the Senate for 5-year terms. The President designates one of the Commissioners to serve as Chairman. The Chairman's tenure is at the pleasure of the President. No more than three Commissioners may be members of the same political party. None can have a financial interest in any Commission- related business.

Stripped of all the extensive regulatory and legal mumbo jumbo, the FCC does three things:

  1. It sets the prices for interstate phone, data and video service.

  2. It determines who can or cannot get into the business of providing telecommunications service or equipment in the United States.

  3. It determines the electrical and physical standards for telecommunications equipment and services. The FCC's powers, although strong, are tempered (limited) by the Federal Courts. Anyone who disagrees with FCC rulings can appeal them to a Federal Court . The FCC's power and rulings are also affected by the Justice Department (The Justice Department changed the industry with Divestiture), Congress and The 50 state public service commissions. The FCC changed with the passage of the Telecommunications Act of 1996 ” the first telecom act passed by Congress since the Communications Act of 1934.

How is the FCC organized? Most items considered by the Commission are developed by one of seven operating bureaus and offices organized by substantive area:

  • The Common Carrier Bureau handles domestic wireline telephony.

  • The Mass Media Bureau regulates television and radio broadcasts.

  • The Wireless Bureau oversees wireless services such as private radio, cellular telephone, personal communications service (PCS), and pagers .

  • The Cable Services Bureau regulates cable television and related services.

  • The International Bureau regulates international and satellite communications.

  • The Compliance & Information Bureau investigates violations and answers questions.

  • The Office of Engineering & Technology evaluates technologies and equipment. In addition, the FCC includes the following other offices:

  • The Office of Plans and Policy develops and analyzes policy proposals.

  • The Office of the General Counsel reviews legal issues and defends FCC actions in court.

  • The Office of the Secretary oversees the filing of documents in FCC proceedings .

  • The Office of Public Affairs distributes information to the public and the media.

  • The Office of the Managing Director manages the internal administration of the FCC.

  • The Office of Legislative and Intergovernmental Affairs coordinates FCC activities with other branches of government.

  • The Office of the Inspector General reviews FCC activities.

  • The Office of Communications Business Opportunities provides assistance to small businesses in the communications industry.

  • The Office of Administrative Law Judges adjudicates disputes.

  • The Office of Workplace Diversity ensures equal employment opportunities within the FCC.

Federal Information Processing Standards

FIPS. The identifier attached to standards developed to support the U.S. government computer standardization program. The FIPS effort is carried out by the U.S. Department of Commerce, Springfield, VA. See the next definition.

Federal Open Market Committee


Federal Reserve Board

The Fed. The federal government agency that sets interest rates and monitors , regulates, and exerts influence over the nation's monetary supply and banking system. It often does this by buying or selling government securities and taking other regulatory actions. The Federal Reserve, the central bank of the United States, was founded by Congress in 1913 to provide the nation with a safer, more flexible, and more stable monetary and financial system. Today the Federal Reserve's duties fall into four general areas: (1) conducting the nation's monetary policy; (2) supervising and regulating banking institutions and protecting the credit rights of consumers; (3) maintaining the stability of the financial system; and (4) providing certain financial services to the U.S. government, the public, financial institutions, and foreign official institutions. www.federalreserve.gov.

Federal Telecommunications Standards Committee

FTSC. A U.S. government agency established in 1973 to promote standardization of communications and network interfaces. FTSC standards are identified by the designator FED-STD. The FTSC's address is General Services Administration, Specification Service Administration, Bldg 197, Washington Navy Yard, Washington DC 20407.

Federal Telecommunications System

FTS. The private network used primarily by the civilian agencies of the federal government to call other government locations and to place calls to phones connected to the PSTN (Public Switched Telephone Network). FTS is a TTTN (Tandem Tie Trunk Network). A TTTN is a large, complex, private switched network which generally involves dedicated COs (Central Offices), as well as dedicated transmission facilities. See also AUTOVON and TTTN.

Federal-State Joint Board

An organization with representatives from the FCC and the state public service commissions which tries to resolve Federal and State conflicts on telecommunications regulatory issues. Sometimes successfully and sometimes not successfully.

Federated States of Micronesia

This is an interesting story about the commercialization of the Internet. The Federated States of Micronesia is a developing island nation in the Western Pacific Ocean, with a population of about 100,000. The country has little need for its Internet TLD (Top Level Domain) of .fm. So, the government of FMS announced on October 8, 1998 a joint agreement with BRS Media to begin registering and marketing the .fm TLD to the broadcasting industry. A number of FM radio stations have paid a lot of money to use the .fm TLD. How's that for e-commerce? See also TLD and Tuvalu.


A television signal source.


  1. The return of part of an output signal back to the input side of the device. Think of the high-pitched squeal you hear when someone brings a microphone too close to the loudspeaker. Not all feedback is as obvious or as irritating . Some feedback is good. See Sidetone, which is what happens when you hear a little in the receiver of you're saying in the transmitter of a phone.

  2. The inevitable result when your baby doesn't appreciate the strained carrots .

Feeder Cable

A group of wires, usually 25-pair or multiples of 25-pair, that supports multiple phones in a single cable sheath. These cables may or may not be terminated with a connector on one or both ends. Feeder cable typically connects an intermediate distribution frame (IDF) to a main distribution frame (MDF). But the term "feeder cable" is also used in backbone wiring. And Bellcore defines the term slightly differently: A large pair- size loop cable emanating from a central office and usually placed in an underground conduit system with access available at periodically place manholes.

Feedback Control

A process by which output or behavior of a machine or system is used to change its operation in order to constantly reduce the difference between the output and a target value. A simple example is a thermostat that cycles a furnace or air conditioner on and off to try and maintain a fixed temperature.

Feeder Line

The cable running between bridges, line extenders and taps.

Feeder Route

A network of loop cable extending from a wire center into a segment of the area served by the wire center.

Feeder Section

A segment of a feeder route that is uniform throughout its length with respect to facility requirements and facilities in place.


Holes punched in paper or papertape which allow the paper or paper tape to be driven by sprocket wheels.


The feedhorn is the focal point of a dish antenna. The feedhorn collects the signals reflected by the dish. The feedhorn is the device used for receiving or radiating microwave signals to or from a parabolic dish reflector.


Software designed to get demand for a product or a new market segment started. Feedware is typically a less-full featured piece of software than the software you're really trying to sell. Feedware typically costs very little. It may even be free. See also Seedware.


First Ended, First Out. A rule for dealing with things in a queue. For example, higher priority messages will be sent before lower priority messages.


Front end interface.

Female Amp Connector

Also called a C Connector or 25-pair female connector. The male version is called a P connector.


One-millionth of a billionth of a second. Femtoseconds are used in laser transmission and in other measures of very small happenings. It's 10 to the minus 15. There are as many femtoseconds in one second as there are seconds in thirty million years . There are 1,000,000,000,000,000 femtoseconds in one second. How small is a femtosecond? In a little more than a second, light can travel from the moon to the earth, but in a femtosecond it only travels one hundredth the width of a human hair.


  1. Front End Processor. The "traffic cop" of the mainframe data communications world. Typically sits in front of a mainframe computer and is designed to handle the telecommunications burden, so the mainframe computer can concentrate on handling the processing burden . Here's a more technical definition: A dedicated communications system that intercepts and handles activity for the host. Can perform line control, message handling, code conversion, error control, and such applications functions as control and operation of special-purpose terminals. Designed to offload from the host computer all or most of its data communications functions. Front end processors are not used in the client/server world.

  2. Fluorinated Ethylene Propylene. Also known by the trade name Teflon, a registered trademark of Dupont, and NeoFlon, a registered trademark of Daikin. FEP is the insulation of choice for high performance cable and wire systems installed in return air plenums. As FEP is really slick, it makes the wire really easy to pull through conduits , around corners, and so on ” the same property that makes it so wonderful in the kitchen. FEP also is fire retardant and produces little visible smoke. FEP is used CAT 5 (Category 5) and higher- rated inside wire and cable systems. FEP's high cost has led many manufacturers to use PVC as an insulating compound, and to coat it with flame retardant compounds . Many countries require the use fire-retardant, low-smoke cable jackets, particularly in plenum ceilings. See also CAT 5, Plenum, and PVC.


Frame Error Rate. A computation based on the number of frames received with errors compared to frames received without errors. See also Frame Error Rate.


  1. Far-End Receive Failure. A yellow alarm. A message from a remote network element that is having trouble receiving a signal.

  2. Far-End Remote Failure. An alarm indicating a failure at the far end of an ATM network, identifying the specific circuit in a failure condition.


A central office in German. In Europe, they call a central office a "public exchange," or just plain "exchange." They look at you kinda strange when you say the North American word, namely "central office."

Ferreed Assembly

A glass enclosed reed relay switch in which the reeds are made of some metal which can be opened or closed by an external magnetic field.

Ferri Chrome

A coating used on tape comprising a layer of ferric oxide particles and a layer of chromium dioxide particles and combining the attributes of both.

Ferric Oxide

A coating used on tape comprised of red iron oxide, the original material used for magnetic recording tapes.


A type of ceramic material having magnetic properties and consisting of a crystalline structure of ferric oxide and one or more metallic oxides, such as those of nickel or zinc. See Barium Ferrite, Hard Ferrite and Soft Ferrite.

Ferroresonant Transformer

A special transformer which puts out regulated AC voltage even when the input voltage is variable. A ferroresonant transformer may be used by itself to correct brownouts or it may be built into a UPS. A ferroresonant transformer has an undesirable characteristic called "high output impedance" which can prevent protective devices such as circuit breakers on equipment plugged into it from functioning, resulting in a possible safety hazard. Another problem is that computer loads applied to ferro based line conditioners or UPS systems cause the voltage waveform applied to the computer to be very distorted , which may result in undervoltage conditions within the computer. Ferro based UPS systems are becoming obsolete because they can become unstable and oscillate when supplying modern power factor corrected power supplies . This definition courtesy APC.


A component of a fiber optic connection that holds a fiber in place and aids in its alignment.


Field Effect Transistor. Very thin and small transistors are used to control pixels in a TFT (Thin Film Transistor ) display.


Far-End CrossTalk. A type of crosstalk which occurs when signals on one twisted pair are coupled to another pair as they arrive at the far end of multi-pair cable system. FEXT is an issue on short loops supporting high-bandwidth services such as VDSL (Very-highbit-rate Digital Subscriber Line), given the relatively high carrier frequencies involved. Services such as ADSL and HDSL, are not affected to the same extent, as the loops are longer and as such interference tends to be attenuated (weakened) on longer loops . See also Crosstalk. Compare with NEXT.


A smaller number. The word "fewer" is always confused with the word "less." 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").


Form Feed. A printer function used to skip to the top of the next page or form.


Fast Fiber Data Interface. A proprietary 100 megabit per second local area network that uses fiber optic, coax, shielded twisted pair or unshielded twisted pair. It is manufactured by PlusNet, Phoenix, Arizona.


Fiber Follow On LAN. Emerging LAN technology.


  1. Fast File Transfer. An ISDN term referring to the fact that file transfers can be accomplished "fast." Reason #1: Two B channels at 64 Kbps each and a D channel at up to 16 Kbps are available to be bonded to provide as much as 144 Kbps. Reason #2: Data transfer is accomplished in an "optimistic" streaming mode, rather than a "pessimistic" packet mode. Therefore, there is no delay associated with acknowledgements. This is possible due to the excellent level of error performance inherent in digital services. The end result is FFT.

  2. Fast Fourier Transform. A signal processing term for a common computer implementation of Fourier Transforms. The FFT, as a practical implementation, will always result in a finite series of sine and cosine waves as an extremely close approximation of the possibly infinite series described by the purely mathematical application of the Fourier Transform. See Fourier's Theorem.

Newton[ap]s Telecom Dictionary
Newton[ap]s Telecom Dictionary
ISBN: 979387345
Year: 2004
Pages: 133

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