We recently installed 3CX 9 on our SBS 2008 box, but we have some trouble making it work consistently. Our problem is mainly one way audio when dialling out, and on some very rare occasions, outside calls not coming in through to our PBX. When dialling out we can 'always' hear the recipient but they can very often not hear us. Our network setup is very simple: We have the PBX on LAN connection to a SIP trunk in WAN. We have a static IP and I've switched of STUN. All ports are afaik forwarded correctly. I suspect our Soincwall TZ 210 is the root of all our trouble, and I wanted to know if anyone here has been able to make this combination work?