asterisk users - Dec 2005 - Echo PSTN Asterisk@Home 2.0 Digium TDM11B & DSL

I have a Digium TDM11B, I'm fighting an issue with with echo on the PSTN
side. I run Asterisk@Home 2.0. I have an analog phone on the FXS channel 1
and Telco on the FXS channel 4. I also have a coupe of softphones, 1 iax2,
the other sip, and a LinkSys Sipura 941. I use a VOIP provider for long
distance. I'm experiencing echo on all calls on any phone for calls going
out over the PSTN, but no echo at all on Long Distance calls with my VOIP
provider or Internal calls. I think its safe to say that echo is occuring on
the PSTN side on channel 4. I've followed the trouble shooting provedures on
voip-info.org for echo cancellation, even calling the local CO using
ztmonitor to adjust rx & tx gain. The only thing I haven't tried yet is
installing shielded cable. I use Verizon DSL for Internet and have the
appropriate filter for my PSTN on channel 4. I'm beginning to wonder if the
problem is due to DSL. Has anyone else had this experience.

Thanks,
David
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
http://lists.digium.com/pipermail/asterisk-users/attachments/20051209/692cfceb/attachment.htm

On Dec 9, 2005, at 9:48 AM, David K Parker wrote:
> I have a Digium TDM11B, I'm fighting an issue with with echo on the 
> PSTN side. I run Asterisk@Home 2.0. I have an analog phone on the FXS 
> channel 1 and Telco on the FXS channel 4. I also have a coupe of 
> softphones, 1 iax2, the other sip, and a LinkSys Sipura 941. I use a 
> VOIP provider for long distance. I'm experiencing echo on all calls on 
> any phone for calls going out over the PSTN, but no echo at all on 
> Long Distance calls with my VOIP provider or Internal calls. I think 
> its safe to say that echo is occuring on the PSTN side on channel 4. 
> I've followed the trouble shooting provedures on  voip-info.org for 
> echo cancellation, even calling the local CO using ztmonitor to adjust 
> rx & tx gain. The only thing I haven't tried yet is installing 
> shielded cable. I use Verizon DSL for Internet and have the 
> appropriate filter for my PSTN on channel 4. I'm beginning to wonder 
> if the problem is due to DSL. Has anyone else had this experience.
>
Have you tried running fxotune on the card?  It's possible that your 
echo problem is related to line impedance mismatch.  For more details, 
see README.fxotune in the zaptel package.

Matthew Fredrickson