asterisk users - Sep 2005 - Silence suppression /RTP VAD and Asterisk? Dropped calls on IP-500

Hello,

I run Asterisk in a 100% VOIP installation with the Polycom IP-500 phones.
Every once and a while I have problems with either dropped calls
between Asterisk and my provider,  or invalid RTP audio streams with
phones behind NAT.  I have had a few Asterisk developers look into my
installation and even my provider check my setup but still am having
problems.  They tell me that I need to disable silence suppression on
the IP-500 because Asterisk won't support it and either Asterisk or
the MG thinks the call is dropped in abstence of RTP packets.

 However I can't find any reference to this in the Polycom manual. 
Does anyone know how to turn VAD/Silence suppression on the Polycom --
or if it even supports it?  Is there a work around with Asterisk? 
Thanks in advance.

David

david.j as wrote:
<snip>
>problems.  They tell me that I need to disable silence suppression on
>the IP-500 because Asterisk won't support it and either Asterisk or
>the MG thinks the call is dropped in abstence of RTP packets.
>
> However I can't find any reference to this in the Polycom manual. 
>Does anyone know how to turn VAD/Silence suppression on the Polycom --
>or if it even supports it?  Is there a work around with Asterisk? 
>  
>
We have it disabled here.  It is in the ipmid.cfg file.  Open up your 
ipmid.cfg file and do a search for VAD.  We have a line like this:

<VAD voice.vadEnable="0" voice.vadThresh="15"/>

To be more specific, look in your ipmid.cfg under the <voice> section.  
That is where you should find it.  Most likely, voice.vadEnable="1" in
your installation.  Change this to 0, save the file, and reboot the 
phones.  If VAD (Voice Activity Detetion) is indeed the cause of your 
problem, it should go away after updating the config and rebooting.

          Jeremy

-- 
Jeremy Gault, KD4NED    <jgault@winworld.cc>
Network Administrator, WinWorld Corporation
Member: Bradley County ACS/RACES/SkyWarn
voice: +1.423.473.8084  fax: +1.423.472.9465
fwd: 461771             msn msgr: jgault@winworld.cc