[Asterisk-Users] Echo in CAPI channels

[Eric Bart]

> If you use a voip technology
> phone such as a softphone or a hard ip phone you will have at an absolute
> minimum an additional 40ms round trip time, but more realisitcally twice 
> that at least. That moves the echo from the sidetone to actually being 
> perceived as an echo.

That what is seems. There always was echo and it was good. But VOIP delays
echo and it becomes a problem.

So we need a good echo canceller. There's no good echo canceller in CAPI.

So if you want CAPI maybe the only solution is to used a hardware based 
echo canceller. I think that it's possible with Eicon Diva cards.

Or if you want to stick with cheap hardware, maybe you can use
"HFC-S PCI chipset based ISDN card, see zaphfc as part of zaptelBRI" 
as from the wiki. Maybe it's possible to use the Asterisk echo canceller
with this driver.

There's also the option of buying an external ISDN to VOIP gateway.
Mediatrix ?

I don't know much about this, I didn't get into it for now. It's 
difficult to get good info about this ...

What is the best way to get a cheap echo-free VOIP to ISDN * PBX ? 
Help anyone ?