[asterisk-users] IAX over two T1 connections bad quality

[Tim Panton]

On 31 Jul 2006, at 22:11, Jerry Geis wrote:

> Help please. I have two systems on the net.
> one in indiana and one in georgia.
> connected with IAX. local SIP phones in each office (10 each) are  
> cisco and running sip.
> TDM04B card in each location has 4 local lines.
> Incoming calls to each location sound fine always.
> The problem is dialing between offices the call quality is BAD.
>
> Both offices are connected to the net with T1 lines. all data.
>
> All phones are setup ulaw 64bit. The IAX connection between the  
> boxes is ulaw 64 bit.
>
> I tried skype between the two offices and talked for 15 minutes and  
> had no issue.
>
> The machine CPU usage is running 92-97% idle most of the time.
>
> Running asterisk 1.2.9.1 and zaptel 1.2.6.
>
> There are switches in the mix that have voice traffic having priority.
>
> How do I determine what is the issue here? Why is the call quality  
> bad and where is
> it that I can tweek.

How have you configured your switches/routers to give voice priority?
Do those rules cover IAX (UDP port 4569)?

To see what asterisk thinks the problem is you can look at
iax2 show netstats
(from memory - I'm off net as I write this)
It tells you how many dropped/late/jittered packets it has seen at  
each end.

You probably want to enable the new jitterbuffer (at both ends) if  
you have not yet.


Tim Panton

www.mexuar.com