I have just upgraded our system from 5.0 to 5.1 build 4078. I backed up the old system before the uninstall of V5.0 and the install of V5.1. When I restored the settings I found I had to re-enter the authentication keys for all the extensions and for the Linksys 3102a gateway. These then worked allright. I have re-entered all the information for Sipgate, and even deleted the provider and created a new entry, but the line fails to register. No entries are made in the server log for registration attempts on this line. My system fails the firewall test in the same way as it did on V5.0:- 1 9000 Error (4) The STUN server returned an ip which is not accessible from outside. addrFromSTUN = XX.XXX.XXX.XX:59545 2 9000 Warning (10) Port is open, but port number has been changed. In many cases, this will present a problem and cause one way audio or no inbound calls. See this FAQ: http://www.3cx.com/support/firewal-checker.html externalAddress = XX.XXX.XXX.XX:59545 However, with V5.0 Sipgate worked perfectly. Anyone got a solution to this?