[Asterisk-Users] IAX choppy sound

[Tim Panton]

On 15 Mar 2006, at 09:02, Stojan Sljivic - GDS wrote:

> Hi,
>
>> Are you using Trunked IAX?
> Currently we do not use trunking.
>
>> How many calls at a time?
> All the test we have performed so far were with only one active call.
>
>> What codecs are you using?
> We have set the bandwith=low, so I think that G.723.1, GSM, and LPC10 
> are in
> the play.

If you have 256kbits/s available and want to make a maximum of 2  calls
you could try something using ulaw (~80kbits/s) anyhow, I would
explicitly set the codec so that you can compare them.
eg:

disallow=all
allow=ulaw


>
>> What is the ping time between the systems?
> Ping stats are:
> Server 1:
> 50 packets transmitted, 50 received, 0% packet loss, time 49491ms
> rtt min/avg/max/mdev = 190.198/213.028/283.275/25.307 ms


> Server 2:
> 50 packets transmitted, 49 received, 2% packet loss, time 49523ms
> rtt min/avg/max/mdev = 190.089/214.855/544.880/59.052 ms
>

That is quite a variation, over an already longish ping time.
you probably need to do some traffic shaping
at your routers to give IAX priority. If you are getting
good results from skype over the same link, you could
try examining the TOS bits in the skype packets and
setting the IAX to use the same TOS bits since that
may be what is making the difference.

>> Any error messages ?
> There are no error messages in the console.

Just to check, can you get decent call quality between 2 IAX clients on 
the same
(local server)?

>
> Regards,
> Stojan Sljivic
>

Hope that helps

Tim