Tom Rymes wrote:
Dan,
If I have followed this thread correctly, your problem
is that, when you pick up a local analog phone connected
to asterisk through a zap channel, asterisk generates
a dialtone, and everything works fine, except that the
echo is intolerable. Then, you install an echo canceller,
and then asterisk cannot reliably register your DTMF
digits when you pick up the phone and dial. In other
words, your problem shows up when you install the echo
cancellers.
Yes you understand correctly.
Do you have the echo cans installed between your local
extension and the zap channel? I assume so, because
otherwise they should have no effect on your DTMF.
Yes
analog phone (Aastra PT390)
|
channel bank (Adtran TA750)
|
T1 echo can (Orion Telecom)
|
Asterisk 1.2.13 (Dell poweredge 1750)
Maybe I'm missing something, but I was always of
the impression that echo cancellers are installed
between asterisk and the PSTN, not between the local
handset and asterisk.
I also have a T1 echo canceller between asterisk and
the pstn. That will help with the echo for SIP phones.
That way, the echo canceller is
only in the media stream when you place a call
out to the PSTN. I assume that you don't have echo
problems calling from one local analog extension to
another.
I do have echo extension to extension! That is the
issue I am trying to eliminate.
If you do, however, I would suggest that
maybe your problem is bigger than just a DTMF issue.
This may be bigger than DTMF. However, since this is
in service, I need to keep it running.
I have worked with Digium and with Orion to try and
resolve this. Digium has ssh into the system on 4
different occasions. Orion assures me that they have
thousands of these same echo cancellers in service but
have never seen the issues I am having.
Some of the things I have done are.
1 - moved TE410P cards to their own interrupts
2 - modified levels in Asterisk, echo cancellers and
channel bank. (I have a few pages of test results.)
I have set levels to Digium recommended levels and to
Orion recommended levels. I have also tried a whole
bunch of other levels. By changing levels, I can get
better results (8% errors instead of 20 or 25%). However,
an error rate above 2% is unacceptable.
3 - turned off vpm support in TE412P card
4 - turned off frame buffer
5 - moved to another server (Dell 1650 poweredge) with
different TE410P cards.
6 - loaded different versions of zaptel and of
asterisk (all in the 1.2.x version)
7 - swapped Digium cards with a spare
Once asterisk recognizes a pressed digit, all of the rest
of the digits are recognized. The only different for the
first digit is the presence of dialtone. That was why
I was trying to reduce the dialtone volume.
Maybe this is not the correct solution. But hey, I need to
try something! The TE412P card with echo cancellers enabled
did not offer satisfactory results. (too much echo).
Don Pobanz
winmail.dat___
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