Grandstream Networks GXW400x User Manual

 

Grandstream Networks, Inc. 

Page 28 of 31  

 

 

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 

 found in many types of devices. Its purpose is to 

control the 

 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 

, specifically 

IPv4, to map 

 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 

 
ATA  Analogue Telephone Adapter. Covert analogue telephone to be used in data network for VoIP, like 
Grandstream HT series products. 
 
CODEC  Abbreviation for Coder-Decoder. It's 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 

 used in 

 and 

communications to fill the 

 time in a transmission resulting from 

. 

 
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 
Telecommunication 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 
duplex (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 
possible 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 
digitally encoded into a 32 Kbit/s signal using Adaptive Differential Pulse Code Modulation.  
 
DNS  Short for Domain Name System (or Service or Server), an 

 service that translates 

 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 
products all have DSP chips built inside. 
 
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 #).