F

Facilities-Based Carrier - FBC
     A carrier that uses its own facilities to provide service, in contrast with resellers, that purchase the services of other carriers  and then retail the services to customers. (Most facilities-based carriers use the services of other carriers to some extent.)

Facility
     A generic term for a logical component of a system (such as a telecommunications channel, a
cross connect, a switch, a  computer, a control center, a building, etc.).  A transmission circuit
between two central offices, or between a central  office and a remote terminal.  Facilities = transmission lines, switches and other physical components used  to provide telephone service.

Fast Packet
     A general term for various streamlined packet technologies including frame relay, BISDN, and ATM.  Compared to X.25 packet  switching, fast packet contains a much reduced functionality, but with the lower overhead, fast packet systems can operate  at higher rates at the same processing cost.

FAX - Facsimile Image Transmission
     There are multiple FAX transmission protocol standards and speeds. The most common standard used on voice-grade dial up  analog networks is Group III at typical speeds from 2400 to 14,400 bps. On Digital Data Service (DDS) and ISDN, Group IV  operates at 56,000 bps.

FCI - Forward Call Indicator
    Identifies the field in an SS7 message, which is set to indicate to participating networks involved in the processing of an LNP call, when an LNP query has been performed.

FCC - Federal Communications Commission
     Regulates interstate communications: licenses, rates, tariffs, standards, limitations, etc. Appointed by U.S. President .

FDDI - Fiber Distributed Data Interface
     A high-speed, optical-fiber-based  token-passing ring LAN interface standard usually operating at 100 Mbps. FDDI is a  fault-tolerant dual counter-rotating-ring design.

FDF - Fiber Distribution Frame
    A cross-connect and/or interconnect system using fiber optic jumpers and cables.

Feature Group - FG
     A Telco Product consisting of Services and Features (e.g. FG-D). In switched access tariffs, it denotes a specific and  uniform type and quality of local exchange access available to interexchange carriers. There are four types:

FG-A
     One Dial-Up Network Circuit via 2-Wire Connection. Line-side switched access connection for originating and terminating  traffic.  Customers of a long distance company that use originating access, must dial a 7-digit local number to reach an interexchange carrier, and then use a tone phone or dialer to dial an identification code plus the phone number they want.

FG-B
     One Dial-Up Network Circuit via 4-Wire Connection (Higher quality than FG-A, extra wires for signaling).  ANI (caller's phone  number) Service is optional.  Trunk-side switched access connection for originating and terminating traffic.  The customers  using FG-B for originating access must dial "950" followed by a "1" or a "0" and the three digit CIC of their long distance  carrier.  Depending on the location, the user may also have to dial an identity code.

FG-C
    A trunk-side switched access connection directly linking local phone company end offices with the long distance network of AT&T.  (Only AT&T has these access connections).

FG-D
     One 1+ Network Circuit via 4-Wire Connection. Also used for 800 Inbound WATS and Travel Card Service.  Provides the "ANI"  (caller's phone number) for billing purposes. A trunk-side switched access connection equal in quality, features and price  to the FG-C connection, and is both originating and terminating calls only within portions of a LATA.  Customers can  pre subscribe to any long distance company and then just dial 1 + the phone number they want.

Fiber
    Any filament or fiber, made of dielectric materials, that guides light. And, is made of transparent materials such as glass, fused silica or plastic.

Fiber Optic
    A glass communications wire which can hold 30,000 times what can be held on copper. Both single-mode and multi-mode are available.

Fiber Optic Terminal - FOT
     Connects copper wire to optical fiber.

File Server
     A process running on a computer that provides access to files for remote user systems.

F-Link
    In SS7, a digital circuit that directly interconnects two service switching points (SSPs) or two service control points (SCPs).

Flush Protocol
    The flush protocol is provided to ensure the correct order or delivery of unicast data frames.

FOC - Firm Order Confirmation
     Vendor response to an Access Service Request (ASR).  A document sent that confirms (or denies) that the service  requested will be provided by the date that was originally requested.

Foreign Exchange (FX)
     A DS-0 line utilizes Feature Group A facilities on one end of the circuit. The Feature Group A service connects a customer  premise in the foreign location with the line side of a BOC central office switch in the U.S. The customer premise end of the  circuit is referred to as the closed end because it terminates on a station instrument, key system, or PBX. The CO switch  end of the circuit is referred to as the open-end because it is open to the public switched network. The open end of the circuit  appears as a local business line in a local exchange, different from (foreign to) the local exchange of the closed end of the circuit. A dial tone from the distant city's local office is heard when this line is accessed, and a local phone number can be  associated with the FX. An FX has fixed monthly charges for the originating local access, IXC, international circuits. Usage  charges are applied through the local telephone company at the open (US) end. The advantages of an FX line are the use of a  local phone number for long distance calls and high volume centralized long distance calling at reduced fixed costs.  In the case of international FX services, the open end must be in the US, unless the foreign PTT can support this service. In many  countries this service falls under regulatory laws.

FOTS - Fiber Optic Terminal System
    A set of transmission equipment and facilities used for optical communications.

FPS - Fiber Protection System
    A system of ducts and supports for organizing and protecting fiber building cables and individual fiber interconnection cables.  Typically includes guides and transition pieces.

Fractional T1 - FT1
     A service that uses a portion of a 24-channel T1 circuit. FT1 allows 64 Kbps increments from 2-channel 128 Kbps through all  24 channels at 1.544 Mbps.

Fractional T3 - FT3
     A service that uses a portion of a 672-channel T3 circuit for any mix of voice, data or broadcast-quality video.

FRAD - Frame Relay Assembler/disassembler
     Used to interface a customer's LAN with the frame relay WAN. This device interfaces LMI
with IPX switch port.

Frame
    A group of bits organized in fields of information.  A field that has been filled with data and is
ready to transmit onto the network is a packet.

FR - Frame Relay

A form of packet switching, but using smaller packets and less error checking than traditional forms of packet switching (such as X.25). Now a new international standard for efficiently handling high-speed, bursty data over wide area networks.

Frame Relay Forum
     Consortium of vendors and consumers of frame relay equipment and services which specifies
Implementation Agreements to  ensure inter operability between multiple vendors' products and services.

Frame Slip (Also called just "slip")
     Any shift of the timing on a circuit. Usually the difference between D4 Super Frame and Extended Super Frame or an  un-framed signal stream. During an out-of-frame condition, one frame slip would increment.

Fraud - Toll Fraud
     A crime in which a hacker obtains telecommunication services by: breaching computer security, using or selling stolen  long-distance credit-card codes, or, accessing a PBX and using its communication facilities illegally. Toll Fraud is estimated to cost U.S. companies $1.2 billion/year.

Frequency Division Multiplexing - FDM
    A multiplexing scheme in which the available transmission frequency range is divided into narrower bands.  Each of these bands is used to carry a separate channel, and is the most common method of multiplexing analog signals.

FTP - File Transfer Protocol (TCP/IP)
     Used to provide file transfers across a wide variety of systems. FTP is an efficient application that only performs the most  basic of file manipulations commands. This application is at the seventh layer of the OSI model.

FT-1
     Fractional digital service hierarchy level 1 with service in multiples of 56/64 Kbps 2 channels
(112/128Kbps) or above, and up  to 23 channels. 256/512/768/1024Kbps are common rates for
this type of service. Also called fractional T1. See LD-1. FT-3  Fractional digital service hierarchy
level 3 with service in multiples of 1.344Mbps. Also called fractional T3.

Full Duplex
     Simultaneous two-way communication path.

Fundamental Mode
    The lowest order mode of a waveguide.

Fusion Splice
    A splice method which joins ends through fusing the two glass surfaces together.