Hi I have setup the 3cx system on a test machine and everything is fine with internal functions. I have set sipgate as my external Voip provider and this register Ok, I can place an external call. However I cannot call to it on the voip number from external phones. It plays a message that the person you are calling is not available. I found another topic on here regarding this and setting incoming calls require authentication, I tried this and when applied the Port/Trunk status becomes Un-Registered. The settings under the voip provider Advanced tab are as follows. Require Registration for incoming Calls Which IP to use in "Contact" Field for registration - External Stun Resolved In the general tab the following is entered SIP Server or host name - sipgate.co.uk SIP server port - 5060 Anyone have any ideas?