Extension to external issue

I have been trying to do some tests with my Elastix distribution. I have trunks, IVR and extensions set up. Everything seemed to be ok while I was testing it to my mobile. When I asked two users to do some tests we found quality issue:

When we call from extension to PSTN we sometimes have quality issue. We can hear the other person perfectly, but all they hear is a ‘drumming’ noise. It occurs when we call some landlines (both VOiP and analog)and some mobile operators.

When that person calls us back they can hear IVR message loud and clear, but when they dial option which switches to the extensions the problem occurs again - our caller hears only noise while we can hear them ok.

The other symptom is in conferences - they work ok no matter who is calling.

Suspecting some codec problem I matched the trunk setting (disallow=all allow=alaw)with that of the extansions but it didn`t help (I have set G.711 in my test phones - Yealink, Gigaset, Alcatel). When I change one trunk (which is used only to dial my mobile - as misc destination - when all other extensions do not answer) to allow alaw, ulaw and gsm I have the same problem when the call is redirected to me - I cannot hear the other person.

I use the latest 32bit Elastix, it runs on VM Ware virtual machine with 1Gb RAM

OUTGOING SETTINGS -Peer details (should work fine according to voip operator):


I was trying to google a solution to my problem but didn`t find anybody with problem like mine.

Is there anything from my config I should post to enable you to help me?

Can anyone help?