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

[Brent Franks]

On Thu, 1 Jul 2004, Mike Benoit wrote:
> Obviously the less I spend the better. But if we have to, a few thousand
> more I guess. The problem I have is that this setup is more of a "trial
> run". Once it works, I'm going to be cloning slightly smaller setups to
> 9 other cities. But they are pretty small, 1 or 2 lines and 2-4 phones
> in each location.  

I totally understand this.  My users complain frequently about echo, and I
am still unable to determine why sometimes it works great, other's it does
not.  The CPU and Memory are powerful enough to handle it, and we rarely
ever see any load on the box.

I too feel this is the major caveat to Asterisk right now.  I am curious
how anyone is achieving a near echo free system.  We are shooting for 1
out of every 300 calls to have echo, which I think can be a realistic
goal.  Given the nature of open source, and the mix-and-match of
components that come up, I can see where Digium is in a hard place to nail
down the cause of every occurance.

> 
> I will only be using POTS lines in each location. 
> 
> The current setup works great besides the echo, and some of the
> information I've read point to the Telco being the issue. If thats the
> case, I should in theory be able to get them to fix the problem. (though
> I could be dreaming)

I think ultimately, if a Mediatrix box, or Cisco box can accomplish echo
cancellation, Asterisk should be able to do it with as much success.
Being that I am not an experienced Programmer, I try not to complain to
loudly.  With my level of involvement, I typically make the business case
to customers and spec out ROI, etc.  I do have a technical background, and
am getting better at trouble shooting Asterisk and working on the source
code.  In fact, subscribing to the CVS list has taken me leap years ahead
of understanding the changes and why they are being committed.

I don't know how much more putting a DSP to handle echo can on the cards
would cost, but if it were 400 - 500 more I would certainly pay it without
a second thought, provided it worked.  Echo, I think, is the largest draw
back to VoIP, and will be the limit to entry into many businesses.  I know
my client, if they were to do it all over again, would choose a regular
TDM (nortel, avaya) solution over the echo they are experiencing.

I think asterisk is definitly headed in the right direction though, and
nothing good comes over night.  So everyone who has worked on it deserves
to be commended.  Without their insight and dedication, we wouldn't even
be talking about this, or have alternatives to turn to.

Regards,

- Brent