Grandstream Networks Grandstream GXV-3000 User Manual download pdf (Page 43)

Grandstream Networks, Inc. GXV-3000 User Manual Page 41 of 46

Firmware 1.0.1.7 Updated: 06/2007

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, de-

pending 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) con-

verter 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 commu-

nications 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

DECIMATE To discard portions of a signal in order to reduce the amount of information to be encoded or

compressed. Lossy compression algorithms ordinarily decimate while sub-sampling.

DECT Digital Enhanced Cordless Telecommunications: A standard developed by the European Tele-

communication Standard Institute from 1988, governing pan-European digital mobile telephony. DECT

covers wireless PBXs, telepoint, residential cordless telephones, wireless access to the public switched

telephone network, Closed User Groups (CUGs), Local Area Networks, and wireless local loop. The

DECT Common Interface radio standard is a multi-carrier time division multiple access, time division du-

plex (MC-TDMA-TDD) radio transmission technique using ten radio frequency channels from 1880 to

1930 MHz, each divided into 24 time slots of 10ms, and twelve full-duplex accesses per carrier, for a total

of 120 possible combinations. A DECT base station (an RFP, Radio Fixed Part) can transmit all 12 possi-

ble accesses (time slots) simultaneously by using different frequencies or using only one frequency. All

signaling information is transmitted from the RFP within a multi-frame (16 frames). Voice signals are digi-

tally encoded into a 32 Kbit/s signal using Adaptive Differential Pulse Code Modulation.

DNS Short for Domain Name System (or Service or Server), an

Internet service that translates domain

names into IP addresses

DID Direct Inward Dialing. The ability for an outside caller to dial to a PBX extension without going

through an attendant or auto-attendant.

DSP Digital Signal Processor. A specialized CPU used for digital signal processing. Grandstream prod-

ucts all have DSP chips built inside.

DTMF Dual Tone Multi Frequency. The standard tone-pairs used on telephone terminals for dialing us-

ing 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 #).

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