[Freeswitch-users] voip-voip echo cancel possible

[Steve Underwood]

Kristian Kielhofner wrote:
> While it might not be feasible it may be possible (and I don't see why not).
>
> There are many, many commercial devices that claim to do this.  Then
> again there are just as many devices that claim to do everything and
> anything...
>   
People tell me commercial offerings claim to do this, but nobody ever 
points me at an example.

There are two key issues that stop EC over VoIP working.

1. There is no way you will ever get EC to work over a low bit rate 
codec. Even if you use nothing but G.711 on your local hop, you have no 
idea what transcoding may occur downstream. So, in the general case it 
won't work however you configure your setup.

2. EC is an adaptive process, requiring is a stable loop length. As soon 
as a jitter buffer somewhere makes an adjustment the EC's tunning will 
blow up. If you are lucky it might eventually retune, but in the 
meantime the pain in your ear could be quite severe. :-)

Steve