conf calling

Unanswered Question
Mar 23rd, 2009

I have a client with UC520 using all four fxo ports.  having issues with conf calling.

Internal user makes first call to an outside party.

Hits conf and then dials another outside party.

The problem is the two outside parties can barely hear each other.  Internal user hears both fine, but first outside caller and second outside caller have a hard time hearing each other.

Please advise.    

I have this problem too.
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Marcos Hernandez Mon, 03/23/2009 - 13:19

Regardless of whether this is software conferencing or hardware conferencing (DSP Farm or DSP on IP phone for 3-way), the audio mixing takes place on the UC500 side. You may want to increase the output signal strength over the FXO and see if that helps:

home-system(config)#voice-port 0/1/0

home-system(config-voiceport)#output attenuation ?
  <-6 - 14>  attenuation in db

Notice that the range is negative 6 to positive 14. Because this is attenuation, a more negative value means a hotter signal (which is what you need). Try a few values and let us know. You need to do  "shut" followed by "no shut" each time you make a change.


Marcos Hernandez
Technical Marketing Engineer
Cisco Systems, Inc.

Marcos Hernandez Mon, 03/23/2009 - 13:22

To add to my last comment, you can also try increasing the input gain on those ports:

home-system(config-voiceport)#input gain ?      
  <-6 - 14>  gain in db

Here, the opposite happens. Positive gain means more signal power. Be careful with the values here. If the signal is too hot, you may start experiencing echo, due to poor power coupling and absorption.


Marcos Hernandez Wed, 04/08/2009 - 12:59

"show voice port" command will give you that information (if you haven't changed the values of course):

UC500#sh voice port 0/1/0

Foreign Exchange Office 0/1/0 Slot is 0, Sub-unit is 1, Port is 0
Type of VoicePort is FXO
Operation State is DORMANT
Administrative State is UP
No Interface Down Failure
Noise Regeneration is enabled
Non Linear Processing is enabled
Non Linear Mute is disabled
Non Linear Threshold is -21 dB
Music On Hold Threshold is Set to -38 dBm
In Gain is Set to 0 dB
Out Attenuation is Set to 3 dB

Echo Cancellation is enabled





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