[Asterisk-Users] Small office setup/using analog lines w/ Ast erisk

[Andrew Kohlsmith]

On Tuesday 23 August 2005 13:25, VaibhaV Sharma wrote:
> * 2 SATA Hdds with H/W RAID (RAID mainly because we plan to do a lot of
> recording on conference calls + fault tolerance)

What good does RAID give you on writes?  None whatsoever.  RAID only helps 
performance on reading.  Fault tolerance aside, I'd get it working first, 
THEN play with RAID.

> 4. Major echo and chit-chat noise issues on random calls. Some of our
> users have calls running for an average of 30 - 40 mins and they were
> experiencing random echo problems to the point that sometimes they would
> leave a voicemail on someone's cell phone and the user would hear only
> echoed voice and nothing else.
>
> Changing the txgain made the echo worse so I had to settle for 0.0 as
> its value. Tried increasing / decreasing echocancel from the default 128
> to 256 or 64/32 but echo got worse both ways. So the only change I could
> make was the rxgain so that call volume was better on this side. Tried
> changing the echotraining values too but that had no effect on the echo.
> At this point, I had rxgain set to 10.5 and txgain set to 0.0.

Run ztmonitor and try to adjust them as described here:

http://lists.digium.com/pipermail/asterisk-users/2004-November/071301.html

Also make these changes to your zaptel Makefile:
add

CFLAGS+=-march=pentium4
KFLAGS+=-march=penitum4

underneath the comments about zconfig.h.  Also you could try defining XLAW as 
described in zconfig.h to optimize for a few zap channels (not sure if few is 
< 8 or not).  Finally, enable MMX in zconfig.h.

Whenever I make those changes I find I get much better echo cancellation 
performance with the stock MARK2 echo canceller.  I don't use echotraining 
because the 800ms silence at the start of every call drives me absolutely 
batty.

> Except the IRQ sharing part, I tried everything in that list and nothing
> seemed to change. Still lot of random echo on calls. Changing the IRQ
> settings was a bit difficult as I only had 2 free PCI-X (now occupied)
> slots for the two digium cards, so changing slots was not an option. I
> disabled the USB subsystem, floppy drive and the onboard SATA
> controller. Even then, one of the digium cards is sharing the IRQ with
> the network controller and I see no way to be able to change that. I am
> thinking of calling dell if this situation persists.

You won't be able to fix that easily, if at all.  sharing IRQs is nasy, 
especially if the ethernet chipset is addicted to poking the microprocessor 
for every little thing it can.

> - Enable the AGGRESSIVE_SUPPRESSOR with MARK2

Agressive mode turns your phones into half-duplex devices.  When you're 
talking, you don't hear ANYTHING from the other side, and vice-versa.  That's 
why you don't hear any echo.

-A.