Yealink SIP-T21 E2 Administrator's Guide

Configuring Audio Features
881
Automatic Gain Control (AGC)
Automatic Gain Control (AGC) is applicable to hands-free operation and is used to keep audio
output at nearly a constant level by adjusting the gain of signals in certain circumstances. This
increases the effective user-phone radius and helps with the intelligibility of soft-talkers.
Voice Activity Detection (VAD)
Voice Activity Detection (VAD) is used in speech processing to detect the presence or absence
of human speech. When detecting period of “silence”, VAD replaces that silence efficiently with
special packets that indicate silence is occurring. It can facilitate speech processing, and
deactivate some processes during non-speech section of an audio session. VAD can avoid
unnecessary coding or transmission of silence packets in VoIP applications, saving on
computation and network bandwidth.
Procedure
VAD can be configured using the following methods.
Central Provisioning
(Configuration File)
<y0000000000xx>.cfg
Configure VAD.
Parameter:
voice.vad
Web User Interface
Configure VAD.
Navigate to:
http://<phoneIPAddress>/servlet?p
=settings-voice&q=load
Details of the Configuration Parameter:
Parameter
Permitted Values
Default
voice.vad
0 or 1
0
Description:
Enables or disables the VAD (Voice Activity Detection) feature on the IP phone.
0-Disabled
1-Enabled
Web User Interface:
Settings->Voice->Echo Cancellation->VAD
Phone User Interface:
None

Yealink SIP-T21 E2 Specifications

General

Brand	Yealink
Model	SIP-T21 E2
Category	IP Phone
Language	English