[asterisk-users] Polycom 301 questions

Lee Jenkins lee at datatrakpos.com
Thu Apr 12 10:27:52 MST 2007

Stephen Bosch wrote:
> Lee Jenkins wrote:
>> Stephen Bosch wrote:
>>> Sidetone can be set in the phone configuration; before you do that,
>>> though, I need to know what you mean by feedback.
>> Sorry, should have been more detailed.  It's a sort of background
>> humming noise, almost like that if you placed the phone next to a high
>> output electric device.  Didn't hear it with Grandstream phone so I
>> thought it may be something I can change in Polycom.  Of course, it
>> could also be that polycom is better phone, but more apt to pick up
>> background noise that
>> It's only on zap calls.  I'm still playing with rxgain and txgain in
>> hopes of resolving this.  Basically, the humming noise increase with
>> volume.
> What were your zapata gain settings before you started tweaking them?


> As far as gain goes -- what about the Polycom phone? Are you using the
> defaults from the SIP firmware package?

Not quite sure as I'm still getting familiar with the phone itself.  I 
would say yes because I did not change any of those settings except to 
specify priority for codecs and to populate Line 1 variables.

> Do you have other analog extensions connected to the line? I had a
> situation in which there was audible humming because there was a fax
> machine connected to the analog line between the Asterisk server and the
> demarcation point.

No, the line goes directly from the phone company terminated jack to the 
the Asterisk box.  I also tried wedging a line filter between the 
Asterisk box and the jack, but no effect.

> Where is the Asterisk server located?

It's located on a shelf in my office.  The only other electronics that 
are close to it is the UPS for it, about 2 feet away.

I' tried playing with the rxgain and txgain again and it sounds like its 
minimalized, but I can still hear it some although it is very low.  It 
is lowest when the call is bridged.  Highest after dial, but before bridged.

Thanks again,


Warm Regards,


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