User guide

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Glossary
Multi-Tech Systems, Inc. MultiVOIP User Guide
Glossary
A
Access: The T1 line element made up of two pairs of wire that the phone company brings to the customer premises. The Access
portion ends with a connection at the local telco (LEC or RBOC).
ACK (ACKnowledgement code) (pronounced "ack"): A communications code sent from a receiving modem to a transmitting
modem to indicate that it is ready to accept data. It is also used to acknowledge the error-free receipt of transmitted data. Contrast
with NAK.
Address: A numbered location inside a computer. It's how the computer accesses its resources, like a video card, serial ports,
memory, etc.
Analog signal: A waveform which has amplitude, frequency and phase, and which takes on a range of values between its
maximum and minimum points.
Analog Transmission: One of two types of telecommunications which uses an analog signal as a carrier of voice, data, video, etc.
An analog signal becomes a carrier when it is modulated by altering its phase, amplitude and frequency to correspond with the
source signal. Compare with digital transmission.
Application Program Interface (API): A software module created to allow dissimilar, or incompatible applications programs to
transfer information over a communications link. APIs may be simple or complex; they are commonly required to link PC applica-
tions with mainframe programs.
ASCII (American Standard Code for Information Interchange) (pronounced "askey"): A binary code for data that is used in
communications and in many computers and terminals. The code is used to represent numbers, letters, punctuation and control
characters. The basic ASCII code is a 7-bit character set which defines 128 possible characters. The extended ASCII file provides
255 characters.
AT Commands: A standard set of commands used to configure various modem parameters, establish connections and disconnect.
The "AT" is used to get the "attention" of the modem before the actual command is issued.
Availability: The measure of the time during which a circuit is ready for use; the complement of circuit "outage" (100% minus %
outage = % available).
B
Backbone: 1. A set of nodes and their interconnecting links providing the primary data path across a network. 2. In a local area
network multiple-bridge ring configuration, a high-speed link to which the rings are connected by means of bridges. A backbone can
be configured as a bus or as a ring. 3. In a wide area network, a high-speed link to which nodes or data switching exchanges
(DSEs) are connected. 4. A common distribution core that provides all electrical power, gases, chemicals, and other services to the
sectors of an automated wager processing system.
Background: An activity that takes place in the PC while you are running another application. In other words, the active user
interface does not correspond to the 'background' task.
Bandwidth: The transmission capacity of a computer channel, communications line or bus. It is expressed in cycles per second
(hertz), the bandwidth being the difference between the lowest and highest frequencies transmitted. The range of usable frequen-
cies that a transmission medium will pass without unacceptable attenuation or distortion. Bandwidth is a factor in determining the
amount of information and the speed at which a medium can transmit data or other information.
Backward Explicit Congestion Notification (BECN): A bit that tells you that a certain frame on a particular logical connection has
encountered heavy traffic. The bit provides notification that congestion-avoidance procedures should be initiated in the opposite
direction of the received frame. See also FECN (Forward Explicit Congestion Notification).
Bell Operating Companies (BOC): The family of corporations created during the divestiture of AT&T. BOCs are independent
companies which service a specific region of the US. Also called Regional Bell Operating Companies (RBOCs).
Binary Synchronous Communication (BSC): A form of telecommunication line control that uses a standard set of transmission
control characters and control character sequences, for binary synchronous transmission of binary-coded data between stations.
Bit (Binary digIT): A bit is the basis of the binary number system. It can take the value of 1 or 0. Bits are generally recognized as
the electrical charge generated or stored by a computer that represent some portion of usable information.
Bps (bits per second): A unit to measure the speed at which data bits can be transmitted or received. Bps differs from baud when
more than one bit is represented by a single cycle of the carrier.
Buffer: A temporary storage register or Random Access Memory (RAM) used in all aspects of data communications which
prevents data from being lost due to differences in transmission speed. Keyboards, serial ports, muxes and printers are a few
examples of the devices that contain buffers.
Bus: A common channel between hardware devices either internally between components in a computer, or externally between
stations in a communications network.