Polycom SIP 3.1 - Manual (Page 202)

Administrator’s Guide SoundPoint IP / SoundStation IP
A - 48
Automatic Gain Control
These settings control the performance of the transmit automatic gain control
feature.
voice.ns.hf.enable 1
voice.ns.hf.signalAttn -6
voice.ns.hf.silenceAttn -9
voice.ns.hf.IP_4000.enable 1
voice.ns.hf.IP_4000.signalAttn -6
voice.ns.hf.IP_4000.silenceAttn -9
Attribute Default
Note Automatic Gain Control will be implemented in a future release.
Polycom recommends that you do not change these values.
Attribute Default
voice.agc.hs.enable 0
voice.agc.hd.enable 0
voice.agc.hf.enable 0