Bad voice Quality on IAX trunk

Asterisk Asterisk Support
1

Hi All,

This is my first poet in this forum. We have two asterisk servers (trixbox ce 2.6.2.3) both were on same versions (1.4.22-4). but recently we upgraded one of the box to Asterisk version 1.8.4.2 and from then, the voice quality is very bad when using the IAX trunk. currently using g711 codec (ulaw) on the trunk. Not sure how to fix this issue.

Can anyone came across this issue?

Thanks,
Premod

2

The most likely cause of poor voice quality is an overloaded network.

The next most likely cause is trying to run Asterisk on a Virtual Machine without giving it adequate resources and avoiding running other processor or memory intensive guests.

3

Thanks for the reply. But I would say honestly, those are not the cases. We are running both th servers on Dell Poweredge hardware, no vms. The bandwidth we have more than enough, means its not choked any time, but we have issue with sound quality all the time.

4

The only other thing that causes that sort of problem only really applies to MOH and voice announcements, and that is failing to provide a timing source. Normal speech has timing from the source.

5

Is there anything related to the dissimilar asterisk versions? I had seen some posts related to that side also in some other forums.

Forgot to mention, we have jitter buffer enabled on both sides and maximum set to 350ms.

6

One normally only has a jitter buffer at a circuit switch boundary. For SIP, the phone normally does that job.

7

Is that really an issue with using dissimilar asterisk versions? I still can’t find a solution for this issue.

8

What does iax netstats have to say , also sineapps used to do a iax2 network test app.

are both systems on the same lan or over a wan.

Ian

9

Both systems (one in US and another in India) are connected through an IPSec VPN tunnel. But there is no latency or over usage issue on the link.
It was fine till we upgrade one box to 1.8. Also iax show netstat not giving any packet loss or drop count. see the sample below

trixbox*CLI> iax2 show netstats -------- LOCAL --------------------- -------- REMOTE -------------------- Channel RTT Jit Del Lost % Drop OOO Kpkts Jit Del Lost % Drop OOO Kpkts IAX2/UStrunk-4642 286 0 40 0 0 0 0 0 0 40 0 0 0 0 0 (None) 1000 0 40 0 0 0 0 0 0 0 0 0 0 0 0 (None) 1000 -1 0 -1 -1 0 -1 0 0 0 0 0 0 0 0 (None) 1000 -1 0 -1 -1 0 -1 0 0 0 0 0 0 0 0 4 active IAX channels

Thanks,
Premod

10

Infact we are getting packet drops when trying multiple IAX channels, see the netstat results below.

trixbox*CLI> iax2 show netstats -------- LOCAL --------------------- -------- REMOTE -------------------- Channel RTT Jit Del Lost % Drop OOO Kpkts Jit Del Lost % Drop OOO Kpkts (None) 1000 0 40 0 0 0 0 0 0 0 0 0 0 0 0 (None) 1000 -1 0 -1 -1 0 -1 0 0 0 0 0 0 0 0 IAX2/UStrunk-16385 285 0 40 0 0 0 0 0 2 80 40 14 2 3 4 IAX2/UStrunk-16386 283 0 40 0 0 0 0 0 3 81 29 0 2 7 2 (None) 1000 -1 0 -1 -1 0 -1 0 0 0 0 0 0 0 0

So what will be the issue? I can assure on both sides, there is no internet bandwidth issue. The loss of packet shows in the remote side (US), so do we need to set something in the US pbx (which is asterisk1.8’) other than the standard configuration?

Please help me…

Thanks,
Premod