[Asterisk-Users] Help with IAX , voice Distortion or Breakage.

[Rich Adamson]

> We have the following problem:
>  
> When calling via iax, the sound is off after a while - most often after 
> about 5 minutes (sometimes later or earlier) - at one end or at both 
> ends. While the channel is up, and packages are still being transmitted, 
> you just can't hear anything. Sometimes you can hear something just a 
> little, but with the voice greatly distorted, sounding like a robot's 
> voice.
> This problem emerges whichever phone is called or whichever phone a call 
> is made from (softphone, ipphone, local phones thru TDM cards)

Without more technical data, its hard to guess. Might consider...

1. if you're using cisco phones, upgrade * to current Head or Stable
on "both" ends of the iax link. The Stable code was just fixed on Friday.
(There could be other phones/adapters that are impacted by the iax/gsm
timestamp problems.) I've also noticed a fair number of other fixes
that were just recently applied to Head.

2. if not cisco phones, check the config's on whatever phone you're using
to ensure "transmit silence" is enabled. If you are using the xten soft
phone, the parameter is in the Advanced Settings area.

3. Check to ensure all ethernet nic adapters (and associated switch ports)
are running in full-duplex mode, etc.

4. If none of the above apply, it would be helpful to see a packet trace
(using ethereal) at about the time the distorting/failure is occurring.