[asterisk-users] Digium TE121P + DAHDI

[Sascha Ferley]

Hi, 

Just trying to figure out / solve some echo issues with one of our systems.
The server is a Dell R710 running Asterisk 1.6.x and Dahdi 2.2.x
The card in the server is a TE121P (with VPMADT032 echo canceller)

We are experiencing some weird echo issues with our Cisco 79xx phones, only
when we are dialing out via the PRI. The echo is like a side tone, where we
can hear ourselves speaking. The other party doesn't hear this however and
its perfectly clean.

After solving some of the IRQ/processing issues in which we seemed to get
HDLC errors pop up after a week and take down the connection completely
(only solvable with a reboot); we changed the smp_affinity settings for all
devices to basically run on their own core.
This seemed to have solved us getting extended IRQ misses and increase in
delays. However it hadn't fixed the echo issue.

After some digging on this it seems that there could be a problem with DAHDI
and I want to get to the bottom of it.
Reference: https://issues.asterisk.org/view.php?id=15724

In my dmesg logs I see that dahdi loads the MG2 echo canceller, is this
correct? I thought that the dahdi firmware for VPMADT032  would take care of
that. Thus I want to insure that we are actually using the hardware module
for echo cancellation and not some software canceller, which is acting
sub-par. 

If this is correct, is there any solution to this problem sofar?

Thanks

S.