[Asterisk-Users] Static and echo on PRI

[Mark Johnson]

Andrew Kohlsmith wrote:

>Try these things:
>
>Software:
>- don't play with gains on PRI or T1 unless you have echo or too loud/quiet.  
>Static isn't caused by screwy gains and on digital circuits it technically 
>shouldn't ever need to be adjusted
>- turn echocancel off for now
>- I notice you've got span=1,0,0 -- if you're talking to the telco make sure 
>you're synchronizing the clock to them.  Use span=1,1,0.
>- remove all modules except those absolutely necessary
>- Have you tried span 2, 3 or 4 instead of 1?
>
>Also is this a *stock* kernel or some distro-"enhanced" version?  Grab a stock 
>kernel of the same version from ftp.kernel.org.
>
>Finally, don't use the agressive canceller unless you REALLY can't get rid of 
>it any other way (I seem to have very good performance with MARK2, using the 
>MMX-friendly implementation (zconfig.h) and making sure my CFLAGS for the 
>zaptel code was optimized for my processor (-march=pentium4).
>
>Also see 
>http://lists.digium.com/pipermail/asterisk-users/2004-November/071301.html.
>
>Hardware:
>- *remove* the TDM22P from the system.  Don't just unload the modules.
>- pull the TE405P out and put it in another (not same motherboard) system.  
>I've seen this clean things up several times.
>
>Wetware:
>It's getting a little late for this now, but you paid for support from Digium 
>when you bought the card; You might want to give them a call.  Unfortunately 
>I don't think this is an issue they will be able to solve over the phone, and 
>their likely recommendation would be to replace the system.  I'd love to know 
>what they do find, if you try this route.
>
>Again, my apologies, for blasting you; I had you mixed up with someone else.
>
>-A.
>  
>
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.

Have not tried a different slot on the quad, will try that tomorrow.

When monkeying with the echo cancel, I never really noticed a 
difference.  I would even reboot the machine between changes to see if 
it made a difference.

I am running this on Fedora Core 1.  I will try any OS you recommend, 
but I have always had great luck with RH type distro's.  I keep 400 and 
500 day uptimes on those machines and they run many, many services.  
Uptimes would be higher but it seems whenever I find a good place to 
work, they close up or I move.  Admittedly, I don't use RPM's for the 
core services, I typically compile those myself.  I also shut down every 
module and service I don't need.  I did alot of reading and it seemed 
like Digium cards were the real deal and I also found many users that 
had luck with the same setup.  Should I try a different approach/OS/system?

Mark