Sorry, I originally posted this in the wrong forum after searching for an answer ... I built a new server (Windows 7) and moved the 3cx config across from a backup, so no changes. I updated the router with the new IP address of the server on all port forwarding. All SIPs are registered, I can make outgoing calls but no incoming calls are routed to the PBX. The firewall checker fails stating "5060 no response received, or port mapping is closed. Port forwarding not configured correctly". But it is the identical configuration which was working before, just forwarding to a different IP address. Any ideas please?