UC540 Echo

Unanswered Question

We replaced our UC520 with a new UC540.  We are experiencing echo when we are on external calls.  It does not matter what line we are on or what phone we are using.  The echo is only heard on our side.  It is not heard on the phone on the other end.  It happens on all external calls.  The echo is a static sounding echo.

The problem did not occur on the UC520.

Any one have any ideas?

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John Platts Mon, 11/23/2009 - 13:59
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I know that the 8.0.0 software pack has been released for the UC540. Is the UC540 running the 7.1.3 release, or is it running the 8.0.0 release? The upgrade to the 8.0.0 release might fix your echo problem.

Dan Smith Wed, 03/17/2010 - 09:08
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I have been experiencing this with several uc540 and uc560's that are running 8.0.  I tested this on my lab uc520 running 7.1.3 and could not hear an echo. as soon as I upgraded to 8.0 I could hear an echo on incoming PSTN calls only. The echo was in the initial 1 or 2 seconds of the call, then it would go away. So far only UC's using FXO ports for PSTN connection are hearing it from what I can tell and it does not happen on every call and it doesn't matter what line its coming in on. I have a tac case open so we will see what comes out of it.

Marcos Hernandez Thu, 04/22/2010 - 07:08
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Try playing with the input gain and output attenuation of your FXO ports in order to adjust this.


How's that done Marcos?

Searching under Bug Toolkit I found a case simular, and it says the issue is the DSP (single) How many DSP's are in the 540 ans are they assigned dedicated to the FXO ports? If so I'm thinking of moving ports to see if the problem is tied to one DSP.

What was the Bug ID for the case opened?

Marcos Hernandez Tue, 05/04/2010 - 09:03
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Hi Bob,

Here is a document that explains the root cause of some echo problems:


You can play around with different gain values. This is done under the "voice-port 0/1/X" CLI for FXO. The commands are "input gain" and "output attenuation". A negative dB value for gain means the signal strength is being diminished, while a negative value in attenuation means it is being amplified. The total signal power is doubled every 3 dB.



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