Polycom SOUNDPOINT SIP 2.2.0 - Manual (Page 159)

Configuration Files
A - 47
Voice Activity Detection <vad/>
These settings control the performance of the voice activity detection (silence
suppression) feature.
Quality of Service <QOS/>
These settings control the Quality of Service (QOS) options.
This attribute includes:
• Ethernet IEEE 802.1p/Q <ethernet/>
• IP TOS <IP/>
Ethernet IEEE 802.1p/Q <ethernet/>
The following settings control the 802.1p/Q user_priority field:
• RTP <RTP/>
• Call Control <callControl/>
• Other <other/>
Attribute
Permitted
Values
Default Interpretation
voice.vadEnable 0, 1 0 If set to 1, enable VAD.
voice.vadThresh integer from 0
to 30 15 The threshold for determining what is active voice and
what is background noise in dB. This does not apply to
G.729AB codec operation which has its own built-in VAD
function.
voice.vad.signalAnnex
B 0, 1 Null If set to 1 and voice.vadEnable is set to 1, Annex B is
used. A new line can be added to SDP depending on the
setting of this parameter and the voice.vadEnable
parameter.
• If voice.vadEnable is set to 1, add attribute line
a=fmtp:18 annexb="yes" below a=rtpmap… attribute
line (where '18' could be replaced by another
payload).
• If voice.vadEnable is set to 0, add attribute line
a=fmtp:18 annexb="no" below a=rtpmap… attribute
line (where '18' could be replaced by another
payload).
If set to 0 or Null, there is no change to SDP.