Short Echo on Incoming PSTN Calls

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ProfTech:
FWIW, I was experiencing this same thing. This was the reason that I got rid of a Cisco SPA-3102 because it is a documented issue for the Cisco and has been on the books for at least 3 years. They don't seem to be supporting the product any more even though they are still selling them. Anyway, I lowered the RX Gain to 3 on the Obi and it seems to have corrected the issue. Be sure you have build 2384 firmware installed in your unit. It is available in this forum.

LeftRight:
The more fundamental way is to match the LINE port AC impedance to your PSTN line. Note, there is a setting on LINE port -

Physical Interface -> LINE port -> AC impedance

The default setting 600 oHm is ideally for a regular PSTN line in US. If you are located outside of US, or you are using some PSTN service but not through regular PSTN line, you may try one of 16 impedance settings, and pick one that minimizes echo if you are experiencing any.

robhouston:
Thanks for the suggestions.  I'm still having a slight problem with it.  The Rx gain doesn't appear to make much difference.  However, I changed the LINE Port AC Impedance value to a significantly lower value, and this improved the echo noticeably.  It's still there, but not quite as prominent. 

I'm still tweaking some of the LINE Port settings, but I haven't seen a big improvement, other than with the AC Impedance value.

Thanks again for the suggestions!

robhouston:
Left/Right------I'm in the US and using a standard CenturyLink PSTN line.  I'm not sure why the standard setting of 600 isn't optimum for my installation, but the lower value worked best for me, after extensive testing.

thanks,

Rob

LeftRight:
Hi Rob, yes, I expect a matched LINE port AC impedance would significantly reduce the echo.

You may keep the default channel gain setting so that the volume on your handset won't get affected.

Other settings on LINE port might not have much to do with echo ...

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