asterisk users - Jun 2004 - Any echo issues with phones from TDM400P > X100P

Hi,
I'm thinking of purchasing a TDM400P card and was wondering if anyone has
experienced any echo issues with phones off these cards connecting to the PSTN
via the X100P cards?
 
I have had my fingers burnt with a Voip phone > X100P.
 
Cheers,
Taff.

		
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taf taffey [tafsjunk@yahoo.co.uk] wrote:
> (Article auto-converted from unnecessary HTML to nice plain text.)
>
> I'm thinking of purchasing a TDM400P card and was wondering if anyone
has
> experienced any echo issues with phones off these cards connecting to the
> PSTN via the X100P cards? 
> 
> I have had my fingers burnt with a Voip phone > X100P.
> 
If I understand you correctly, you propose to replace your "Voip
phone" (using SIP or whatever) with a phone plugged into a FXS
port.

I doubt that that will make any difference, as the echo problem is
most likely caused by your FXO (the X100P and its driver) or your
related setup.

As I understand it, the new FXO modules for the card you mentioned
don't have hardware echo detection (correct me if I'm wrong) so
using one of those in place of the X100P probably won't help either.

You should experiment with your configuration settings for the FXO
card.  Check your gain values etc.  If you don't have any luck with
that then try changing your zconfig.h to switch on CONFIG_ZAPTEL_MMX.
You can also play with the AGGRESSIVE_SUPPRESSOR switch (same file).

There are lots of other ideas in the mail list archives.

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> Hi,
> I'm thinking of purchasing a TDM400P card and was wondering if anyone
has
> experienced any echo issues with phones off these cards connecting to the 
> PSTN via the X100P cards?
>  
> I have had my fingers burnt with a Voip phone > X100P.
I replaced two x100p's with a tdm04b 4-port fxo card, and the echo problem
with pstn lines are absolutely no different; echo is still there and I've
spent a substantial amount of time attempting to improve it (as an ex-
telco engineer). Three pstn lines from two central offices all identical.
Attaching these same three pstn lines to a Mediatrix 1204 totally 
eliminated all echo, however the 1204 had other problems that caused 
me to return it to the reseller. Tried ever combination of echo cancellation
options in Make and *.h files that folks have suggested, problem is
still there and most disturbing during the first 15 seconds of all calls.

As a non-programmer and * user for over nine months, its my opinion (right,
or wrong) that past echo problems have had two sources; one from pstn 
mismatch problems that have been heavily discussed since about September 
2003. The other source has not yet been found/diagnosed and "seems" to
be system dependent (and its not irq related either). You either have
it or you don't, and the few developers that have either the x100p or
the tdm card installed, don't seem to have the problem. Therefore diagnosing
the root cause is still waiting on someone with the problem _and_ the
programming skills.