I'm testing 3CX, and things seem pretty good, except we can't receive incoming calls. We have a Draytek 2955 behind 2 x Draytek ADSL modems and 2 x ADSL. I have followed the excellent instructions on the 3CX support pages for the Draytek 2820: http://www.3cx.com/blog/voip-howto/draytek-firewall-voip/ ... the 2955 menus are identical. I have run the firewall checker, it completed successfully. Sip trunk provider is Gradwell. They are very helpful but are not familiar with 3CX. There is just one inbound number (no DDI). We are just using the 3CX softphone for now, and it works internally between extensions and can call outbound. Basically outbound calls work, but with inbound calls the caller doesn't get a ring tone, the line is silent. There is no activity in the 3CX log at the time the call is made. I can see that I might not have got the inbound DDI configuration configured properly, but since there is no log activity I don't think the inbound call is getting beyond the firewall. A very nice lady at 3CX has also told me that 99% of 3CX problems are firewall problems, which I can well believe. Any ideas what to try next?