[cisco-voip] adjust volume vic2-4fxo

[Robert Kulagowski]

Michael Thompson wrote:
> To make inbound calls louder, on the FXO Port itself, type 'input gain X'.
> positive numbers make it louder and lower (negative) make it quieter.
> 
> Counter-intuitive to that is for 'output attenuation X', higher numbers make
> output quieter (attenuation is a dampening/loss of signal) and lower
> (negative) numbers make it louder.
> 
> You REALLY have to watch about over driving the signal though.  That's where
> you could cause static and echo issues.  

Ditto.  I had issues where entering DTMF was problematic which we 
eventually traced to sending too hot a signal to the PSTN, which caused 
EC to fail, so the echo of the DTMF was picked up by the remote end as 
an additional keypress.  Caused no end of problems.