yep I was just about to say the same thing. VOIPo seems to work best when you set the port to 5060 for the registrar server port. You can change the proxy server port to whatever you like (at least that is fine with my set up). I also have sip.voipwelcome.com (or whatever server you are using) under the registrar sever field.

My Advanced settings are the same, I've actually set G722 as my first codec (though I know it won't really work) as well as keeping G711/G729 underneath; so I don't think you have to force the codec to make it work. Other then that everything else is the same.

Could the issue possibly be with your router? I know I had trouble getting this to work with my old Trendnet, but now that I'm using the Zyxel X550N I haven't had any issues.