0, this variable tells FreeSWITCH to transmit comfort noise when idle. The value of this variable is set to the divisor of the silence generating function.
1400are common values set, but you may experiment with other choices to pick one that sounds best.
true, FreeSWITCH will pick a default comfort noise value.
-1, FreeSWITCH will transmit silence without comfort noise.
<action application="set" data="send_silence_when_idle=400"/>