Polycom SoundStructure C16 Design Manual page 468

Design Guide for the Polycom SoundStructure C16, C12, C8, and SR12
set mute "Mics" 0
The in-room volume for the remote audio may be increased with the fader
command on the phone or video codec audio as follows.
inc fader "VSX8000 In" 1
inc fader "Phone In" 1
to increase the gain on the faders - making the "VSX8000 In" and "Phone In"
channels louder in the local room.
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