UC520 Call Forwarding - audio quality

[bruce]

Internal extension is set to Forward All Calls to cell phone (perhaps the critical piece of data).

The call forwarding functions properly but the parties to the call can not hear each other.

What, if anything, can be done to enhance the audio to a functional level?

[mikeall · Accepted solution]

Most of the time that issue is due to the "CO Line" voltage levels that could have anything to do with the UC520's disctance from your local CO (Central Office) to repeaters or pedastals in between the system and CO. I would start with the local dialtone provider and ask them to meter the analog lines and provide you with the levels and verify they are compatible with the UC520's FXO/ CO requirement. more info here: https://www.myciscocommunity.com/message/4793#4793

To get the volume levels you are after you may need to move toward some form of digital or IP dialtone, i.e.. T1/ PRI or SIP trunking.

Also check www.cisco.com/go/smallbizsupport for more info.

Good Luck,

MA

[bruce]

Good information.

AT&T has checked voltages and provided the following -

50 volts per line (max level)

16-26 stress.

Could you help narrow my search for the appropriate UC500 documentation to learn what the desired voltages are?

Can you translate what is to be gleened from a 16-26 stress?

[Marcos Hernandez]

Is it low volume or no audio what you are experiencing?

Thanks,

Marcos

[bruce]

It is low volume to the extent that neither party can be heard.

"Noise" can be heard but it is inaudible

[Marcos Hernandez]

There is a link inside this thread taht explains how to modify the gain on the FXO trunks to improve volume levels:

https://www.myciscocommunity.com/message/12072

Let us know how it goes.

Marcos

[David Trad]

Hi Bruce,

It is low volume to the extent that neither party can be heard.
"Noise" can be heard but it is inaudible

I know of the issue you are talking about and have experienced it myself, i cant remember the exact remedy as it was a while ago when i had to deal with it, but i am almost certain we had to force a particular codec to be used, the reason was because it was coming in over an analogue line, then going out over one to a Digital Cell Network, the different types of Codecs being used through the whole process had an impact on the voice quality (Very low volume with static at times).

If there is a way for you to force the G-711 aLAW/uLAW codec from incoming to outgoing give that a try, if that does not work try and force the G-729 Codec (Which will involved transcoding).

I cant remember the exact remedy and i dont have access to that particular machine any loger to see what we did, i normaly keep running configs but i never took a backup before i left my previous place of work.

Even if this is a call forward from an internal extension we still had to force a codec, i never understood why as it was the first time i had seen this problem, but i have to assume that it had something to do with the way the Telco provioned that line, i had my suspecions that it was because they were using pair gains, or some other dodgy work on the lines.

Cheers,

David.