[Asterisk-Users] UPDATE - Echo cancellation, when software doesn't cut it. Whats next?

[Nicolas Bougues]

> 
> So the two questions remain. 
> 
> 1. Why do incoming calls have nearly no echo (sound great), and outgoing
> calls are bad during the first 30 seconds, and okay (but not good) after
> that. 
> 
> 2. Why do outgoing calls to cell phone numbers sound great?
> 
> Seeing as an outgoing call to a land line has echo, but the same land
> line calling in has virtually no echo, does this point the finger at
> Asterisk code having issues?
> 

Echo (most often) comes from hybrid circuits on PSTN lines (2 wires
<-> 4 wires transformation).

Cell phones, as well as some corporate digital phones don't go through
that kind of devices, so there is no echo generated. So, basically, no
echo cancellation required. Unfortunatly, it's impossible to know from
the caller point of view whether the call will need echo cancellation
or not.

-- 
Nicolas Bougues
Axialys Interactive