[Asterisk-Users] Static and echo on PRI

[Adam Goryachev]

On Wed, 2005-04-27 at 00:03 -0400, Mark Johnson wrote:
> Andrew Kohlsmith wrote:
> 
> This is perfect stuff!!!  Thank you!!  I actually pulled the TDM22P 
> today, removed all of those drivers and get the same results.  I have 
> built another box and am installing asterisk as we speak.  I tried the 
> span=1,1,0 with the same results and have been running that line for a 
> day now.  What I find strange is this...  If I speak at a normal tone, 
> it sounds OK.  I still get static noise when the other person speaks.  
> If I talk louder, I start to get what sounds like a partial echo.  If I 
> yell, I get a definite echo.

This sounds vaguely similar to a problem I had over a year ago. I
progressively solved it by:

*) New motherboard/CPU (from via based AMD XP1800 to via based dual AMD
Athlon MP based)
*) Lots of playing with echo canceller options

Those two solved the static problem, and most of the time, they solved
the echo problem.

However, I recently had the opportunity to swap my card for a new TE4xxp
card, and found that all my intermittent problems vanished (timing
slips, frequent red alarms, dropped calls, HDCL errors). After a few
more weeks, I got the card RMA'ed, and now everything is perfect. No
frame slips, no echo, no static, nothing at all.

BTW, the 'static' in my case was only ever heard by the PRI party, the
sip/etc user never heard it. The way it seemed to work is while I
talked, the remote party would hear me overly amplified + some
distortion factor... Even though the actual volume wasn't loud... It
made it difficult to have a conversation, and some people would simply
hangup (annoying after you have been on hold for 40 minutes). However,
this wasn't apparent on ALL calls, it only affected some calls, but
always the same people were affected.

So, it seems to me that the real problem was some sort of marginal card,
but by throwing a better motherboard/CPU at it, I was able to get better
performance...

My suggestion, try another motherboard, and then contact digium, get
them to run zttest and also do a loopback test. It was the loopback test
that got them to replace my card (it received less than 10% of the
packets it sent without error, the other 90% or more were errors!
Honestly, I'm surprised it even worked some of the time).

Hope that helps you somewhat...

Regards,
Adam
-- 
 -- 
Adam Goryachev
Website Managers
Ph:  +61 2 8304 0000                        adam at websitemanagers.com.au
Fax: +61 2 9345 4396                        www.websitemanagers.com.au