Just giving 3cx my first kick at the can. In running the Firewall Checker, phase 2a fails immediately. Code: <16:54:46>: Phase 2a, Check Port Forwarding to UDP SIP port, please wait... <16:55:06>: UDP SIP Port is set to 5060. NO RESPONSE received. Phase 2a check FAILED. Application exit code is -2 However, if I randomly change the ports on the Firwall Checker prompt to 5067: Code: <16:55:43>: Phase 2a, Check Port Forwarding to UDP SIP port, please wait... <16:55:58>: UDP SIP Port is set to 5067. Response received correctly with no translation. Phase 2a check passed. <16:55:58>: Phase 2b. Check Port Forwarding to TCP SIP port, please wait... <16:55:58>: TCP SIP Port is set to 5067. Response received correctly with no translation. Phase 2b check passed. This is 3cx free on a windows XP box. The router/firewall is just a consumer grade D-Link (DIR-655). Port Forwarding is setup in the router for 5060 TCP/UDP, 5090 UPD, and 9000-9005 UDP using ip range 10.0.0.x / subnet 255.0.0.0 ( if that helps) Since the 5067 attempt doesn't even have the port forwarding set in the router, so strange... Any ideas or assistance appreciated.