Facilities-Based Carrier - FBC
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.)
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.
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
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
FDF - Fiber Distribution Frame
cross-connect and/or interconnect system using fiber optic jumpers and
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:
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.
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
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).
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.
Any filament or fiber, made of
dielectric materials, that guides light. And, is made of transparent
materials such as glass, fused silica or plastic.
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
copper wire to optical fiber.
A process running on a
computer that provides access to files for remote user systems.
In SS7, a digital circuit that
directly interconnects two service switching points (SSPs) or two service control points (SCPs).
The flush protocol is
provided to ensure the correct order or delivery of unicast data frames.
FOC - Firm Order Confirmation
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
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
FRAD - Frame Relay Assembler/disassembler
Used to interface a customer's LAN with the
frame relay WAN. This device interfaces LMI
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
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
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.
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
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.
The lowest order mode of a
A splice method which joins
ends through fusing the two glass surfaces together.