IAX hardphones behind NAT router

I am having some trouble with using an IAX2 hardphones behind a NAT router. Are there any settings in iax.conf that I should be aware of that I am missing. I have set tos=reliability for one thing and qualify=yes but this seems to have made little difference.



Just an update. I have three people using IAX2 phones. Two of these are on BT Broadband here in the UK, and another is using Tiscali (which I suspect is a BT Wholesale DSL line). Now get this. The BT lins keep falling over repeatedly. The Tiscali line stays sweet. We can maintain connection ad infinitum.

We have switched aruond routers between different sites and the symptoms stay with the BT lines, ie, they are crap.

The BT ones keep crapping out. Do BT nobble VOIP traffic on their lines in order to push their owen VOIP services?



If you are suspecting them of purposely slowing VOIP traffic, and you have control over the endpoints, you should try to tunnel the VOIP traffic through a vpn to see if that eliminates the issue.

It is not that they are slowing traffic. We get effects whereby the dialling phones think that the call has not been set up but speaking is possible.

When you dial a number the display on the phone says ‘dialling’. Then when the recipient of the call answers the display should change to ‘talking’. This is what happens on a good day on the Tiscali broadband. When we do this via Demon or BT Broadband, the display does not change from ‘dialling’ The call then cuts off after exactly 1:30.

Any ideas?