hi! i have the following problem. i'm using 3cx with stun server installed on the same machine. i'm trying to make a call through the internet from another lan sitting behind the nat. i'm using x-lite, the extension is amrked as external and bind to media server. i've got ports 5060, 3478, 7000-7500 opened. the call is establishing but none of the parties are hearing each other. any suggestions on the problem?