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GLV-540 User Manual
7.7 Appendix G: Glossary of VoIP Terms
ADSL Asymmetric Digital Subscriber Line: Modems attached to twisted pair copper
wiring that transmit from 1.5 Mbps to 9 Mbps downstream (to the subscriber) and
from 16 kbps to 800 kbps upstream, depending on line distance.
AGC Automatic Gain Control is an electronic system found in many types of devices.
Its purpose is to control the gain of a system in order to maintain some measure of
performance over a changing range of real world conditions.
ARP Address Resolution Protocol is a protocol used by the Internet Protocol (IP)
[RFC826], specifically IPv4, to map IP network addresses to the hardware addresses
used by a data link protocol. The protocol operates below the network layer as a part
of the interface between the OSI network and OSI link layer. It is used when IPv4 is
used over Ethernet
ATA Analog Telephone Adapter. Used to convert analog telephone signal in order to
use a VoIP data network.
CODEC Abbreviation for Coder-Decoder. It is an analog-to-digital (A/D) and digital-
to-analog (D/A) converter for translating the signals from the outside world to digital,
and back again.
CNG Comfort Noise Generator, generate artificial background noise used in radio and
wireless communications to fill the silent time in a transmission resulting from voice
activity detection.
DATAGRAM A data packet carrying its own address information so it can be
independently routed from its source to the destination computer
DNS Short for Domain Name System (or Service or Server), an Internet service that
translates domain names into IP addresses
DSP Digital Signal Processor. A specialized CPU used for digital signal processing.
DTMF Dual Tone Multi Frequency. The standard tone-pairs used on telephone
terminals for dialing using in-band signaling. The standards define 16 tone-pairs (0-
9, #, * and A-F) although most terminals support only 12 of them (0-9, * and #).
FQDN Fully Qualified Domain Name. A FQDN consists of a host and domain name,
including top-level domain.
DHCP The Dynamic Host Configuration Protocol (DHCP) is an Internet protocol for
automating the configuration of computers that use TCP/IP. DHCP can be used to
automatically assign IP addresses, to deliver TCP/IP stack configuration parameters
such as the subnet mask and default router, and to provide other configuration
information such as the addresses for printer, time and news servers.
ECHO CANCELLATION Echo Cancellation is used in telephony to describe the
process of removing echo from a voice communication in order to improve voice
quality on a telephone call. In addition to improving quality, this process improves
bandwidth savings achieved through silence suppression by preventing echo from
traveling across a network.
There are two types of echo of relevance in telephony:
Acoustic echo and hybrid echo. Speech compression techniques and digital
processing delay often contribute to echo generation in telephone networks.
HTTP Hyper Text Transfer Protocol; the World Wide Web protocol that performs the
request and retrieves functions of a server
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