Multi-Tech Systems MTA128NT - Manual (Page 60)

Glossary
MTA128ST/NT 60
bus—A common channel between hardware devices, either inter-
nally between components in a computer, or externally between
stations in a communications network.
byte—A unit of information consisting of eight binary digits (bits).
A byte holds the equivalent of a single or character (such as the
letter A).
C
Call Bumping—TA feature that reallocates the second B-channel to
an analog port when both B-channels are in use. If you are perform-
ing a data transfer using both channels and need to make a phone
call, one channel is dropped to handle the call and then is reestab-
lished after it is completed. With call bumping you don’t miss any
calls.
call setup time—The time to establish a circuit-switched call
between two points. Includes dialing, wait time, and central office–
long distance service movement time.
carrier signal—An analog signal with known frequency, amplitude
and phase characteristics used as a transport facility for useful
information. By knowing the original characteristics, a receiver can
interpret any changes as modulations, and thereby recover the
information.
Centrex—A multi-line service, offered by telephone companies,
that provides functions and features comparable to those of a PBX
for large business users. See also PBX, exchange.
channel—A data communications path between two computer
devices. It can refer to a physical medium (e.g., UTP or coax), or to
a specific carrier frequency. In ISDN, two types of channels are
specified: transparent (user can define the service), and
nontransparent (service is assigned protocols for specific network
functions). ISDN channel names are designated by a single letter,
from A through M, sometimes combined with a number (see B-
channel and D-channel).
CHAP(Challenge Handshake Authentication Protocol)—Security
method used to verify the identity of a person or process.
CHAP MD5—Chap with MD5 digital signature algorithm imple-
mented.
circuit-switched network—A technology used by the PSTN that
allocates a pair of conductors for the exclusive use of one communi-
cation path. Circuit switching allows multiple conversations on one
talk path only if end users multiplex signals prior to transmission.
circuit switching—The temporary connection of two or more
communications channels using a fixed, non-shareable path through
the network. Users have full use of the circuit until the connection is
terminated.
CO (central office)—The lowest, most basic, level of switching in
the PSTN (public switched telephone network). A business PABX or
any residential telephone connects to the PSTN at a central office.
COM port—A serial communications port on a personal computer.
Normally, there are two: COM1 and COM2.
CPE (customer premise equipment)—The generic term for data
communications and/or terminal equipment that resides at the user
site and is owned by the user (e.g., not telephone company equip-
ment).
D
DCE (data communications equipment)—Any device that serves as
the port of entry from the user equipment to a telecommunications
facility. A modem is a DCE for the telephone network (PSTN) that is
commonly on site at the user’s premises. Packet Switched Networks
have another level of DCE that is most often located at a central
office.
D-channel—A non-ransparent digital ISDN channel that operates at
16K or
64 Kbps, used for call control signalling, along with one or more B-
channels. The D (demand) channel signal can control call setup, call
teardown, and invocation of Supplementary Services. Is also used
for telemetry and for low-speed, low-priority packet-switched data.
Contrast with B-channel.
default—A preset value or option in software packages or in hard-
ware configuration that is used unless you specify otherwise.
device driver—Software that controls how a computer communi-
cates with a device, such as a printer or mouse.
digital data—Information represented by descrete values or condi-
tions (contrast analog data).
digital PBX—A private branch exchange that operates internally on
digital signals. See also exchange.
digital signal— A discrete or discontinuous signal (e.g., a sequence
of voltage pulses). Digital devices, such as as a series of electrical
pulses that have discrete jumps rather than gradual changes.
digital transmission—A method of electronic information transmis-
sion common among computers and other digital devices. Because a
digital signal may be only high or low at any given time, noise and
distortion can easily be removed from digital transmissions.
digitize—To convert an analog signal to a digital signal.
DIP switch—Pronounced dip switch. A set of tiny toggle switches,
built into a DIP (dual in-line package), used for setting configurable
parameters on a printed circuit board.
DN (directory number)—The phone number assigned to an ISDN
TA at subscription time. It is a string of up to 24 characters, consist-
ing of the valid dialing characters (0-9, *, and #).
driver—A software module that interfaces between the operating
system and a specific hardware device (e.g., color monitors, printers,
hard disks, etc.). Also known as a device driver.
DTE (data terminating equipment)—A term used to include any
device in a network which generates, stores or displays user infor-
mation. DTE is a telecommunications term that usually refers to
PCs, terminals, printers, etc.
DTMF (dual-tone multifrequency)—A generic push-button concept
made popular by AT&T TouchTone.
DTMF detection—A capability in some fax/data modems that can
differentiate between DTMF or fax calling tones. A typical applica-
tion would be a program that routes calls to specific communica-
tions applications, depending either on the type of call or on a
DTMF tone added to a dialing string.
E
EEPROM (Electrically Eraseable Programmable Read-only
Memory)—Upgradable memory chip often used to store firmware.
EISA (Enhanced Industry Standard Architecture)—Pronounced
eesa. The purpose of the EISA bus is to provide a 32-bit bus for
faster throughputs while maintaining backward compatibility with
the classic ISA bus architecture.
ET (exchange termination)—The carrier’s local exchange switch.
Contrast with LT (loop termination).
exchange—A unit (public or private) that can consist of one or more
central offices established to serve a specified area. An exchange
typically has a single rate of charges (tariffs) that has previously