User guide

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Glossary
Multi-Tech Systems, Inc. MultiVOIP User Guide
Digital Data: Information represented by discrete values or conditions (contrast "Analog Data").
Digital Loopback: A technique used for testing the circuitry of a communications device. Can be initiated locally, or remotely (via a
telecommunications device). The tested device decodes and encodes a received test message, then echoes the message back.
The results are compared with the original message to determine if corruption occurred en route.
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 terminals and
computers, transmit data as a series of electrical pulses which have discrete jumps rather than gradual changes.
Digital Transmission: A method of electronic information transmission common between computers and other digital devices.
Analog signals are waveforms: a combination of many possible voltages. A computer's digital signal can be only "high" or "low" at
any given time. Therefore, digital signals can be "cleaned up" (noise and distortion removed) and amplified during transmission.
Driver: A software module that interfaces between the Operating System and a specific hardware device (i.e. color monitors,
printers, hard disks, etc.). Also known as a device driver.
Drop and Insert: The process where a portion of information carried in a transmission system is demodulated ("Dropped") at an
intermediate point and different information is included ("Inserted") for subsequent transmission.
DTE (Data Terminating Equipment): A term used to include any device in a network which generates, stores or displays user
information. DTE is a telecommunications term which usually refers to PCs, terminals, printers, etc.
DTMF (Dual-Tone MultiFrequency): A generic push-button concept made popular by AT&T TouchTone.
E
E&M: A telephony trunking system used for either switch-to-switch, or switch-to-network, or computer/telephone system-to-switch
connection.
EIA: The Electronics Industries Association is a trade organization in Washington, DC that sets standard for use of its member
companies. (See RS-232, RS-422, RS530.)
Encapsulation: A technique used by network-layer protocols in which a layer adds header information to the protocol data unit
from the preceding layer. Also used in "enveloping" one protocol inside another for transmission. For example, IP inside IPX.
Endpoint: A terminal, Gateway, or MCU (MultiPoint Control Unit).
Ethernet: A 10-megabit baseband local area network that allows multiple stations to access the transmission medium at will
without prior coordination, avoids contention by using carrier sense and deference, and resolves contention by using collision
detection and transmission. Ethernet uses carrier sense multiple access with collision detection (CSMA/CD).
Excess Zeros: A T1 error condition that is logged when more than 15 consecutive 0s or less than one 1 bit in 16 bits occurs.
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 been approved by a regulatory group.
Exchange Area: A geographical area with a single uniform set of charges (tariffs), approved by a regulatory group, for phone
services. Calls between any two points within an exchange area are local calls. See also "Digital PBX", "PBX".
Exchange Termination (ET): The carrier's local exchange switch. Contrast with "Loop Termination - LT".
Explicit Congestion Management: The method used in frame relay to notify the terminal equipment that the network is overly
busy. The use of FECN and BECN is called explicit congestion management. Some end-to-end protocols use FECN or BECN, but
usually not both options together. With this method, a congestion condition is identified and fixed before it becomes critical.
Contrast with "implicit congestion".
F
Failed Seconds: A test parameter where the circuit is unavailable for one full second.
Fax (facsimile): Refers to the bit-mapped rendition of a graphics-oriented document (fax) or to the electronic transmission of the
image over phone lines (faxing). Fax transmission differs from data transmission in that the former is a bit-mapped approximation of
a graphical document and, therefore, cannot be accurately interpreted according to any character code.
Firmware: A category of memory chips that hold their content without electrical power, they include ROM, PROM, EPROM and
EEPROM technologies. Firmware becomes "hard software" when holding program code.
Foreground: The application program currently running on and in control of the PC screen and keyboard. The area of the screen
that occupies the active window. Compare with "background".
Frequency: A characteristic of an electrical or electronic signal which describes the periodic recurrence of cycles. Frequency is
inversely proportional to the wavelength or pulse width of the signal (i.e., long wavelength signals have low frequencies and short
wavelength signals yield high frequencies).