[asterisk-users] Extremely choppy sound on some of ourPOTSnetwork calls; goes away with mute

[Rich Adamson]

Noah Miller wrote:
>>>> You can also change some settings in the zapta and zaptel
>>>> config.. to reduce
>>>> echo and interference on the line..
>>>
>>> This is the most important thing here - what does your zapata.conf look
>>> like?
>>>
>>  zapta.comf
>>  switchtype=national
> 
> This is not necessary in your case.  It pertains to PRI lines, and not
> the POTS lines you have.
> 
> 
>>  echocancel=yes
>>  echotraining=yes
>>  echocancelwhenbridged=yes
> 
> You may want to turn each of these off, in turn, for testing,
> especially the "echocancewhenbridged".
> 
> You can also tune the "echocancel" setting in terms of taps (a tap is
> one sample from the data stream per second).   You can use the values:
> 16, 32, 64, 128, or 256 ('yes' just means 128).

Might also try echotraining=800. That parameter causes the zaptel code 
to wait 800 milliseconds before pulsing the pstn line, and that pulse 
return is used to preload the software echo canceller to some reasonable 
starting point. Not usre if this will have any impact on your problem, 
but might be worth a try.