[Asterisk-Users] Intermediary jitter buffering

[steve at daviesfam.org]

On Sat, 12 Feb 2005, Michael Giagnocavo wrote:

> Hello,
> 
> 	I understand that only the destination of a call should do jitter
> buffering. So, if IAX2/PhoneA calls IAX2/PhoneB through my server (no
> transfers), PhoneA and PhoneB need to perform their own jitter buffering,
> and Asterisk will just forward the frames, correct?
> 
> 	What happens if the peer does not support jitter buffering, but is
> close by so there's no need for jitter buffering? My situation is that I
> have an Asterisk machine right in front of our provider's systems (same
> switch, < 1ms latency). If they don't have jitter buffering, how can I force
> my Asterisk machine to jitter buffer calls from my users to them?



Interesting question.  Its an issue when you set up a IAX link between two 
"close by" peers.  You tend to think that you don't need jitter buffer, or 
can set the settings down low.  But if you take a call from that close-by 
peer that actually comes from somewhere else, and you suddenly might need 
a big buffer.

So it would be nice if JB setting could somehow by negotiated.

Anyway - a trick that comes to mind to get your packets dejittered before 
sending to the other box is to interpose a Local channel.

So - when you handle the incoming call, on your intermediary machine, 
rather than Dial() the third box, rather dial a Local/ channel that then 
dials to 3rd machine in turn.

Then, chan_iax2 will by bridged to the local/ channel, and will dejitter.

Regards,
Steve