I configured 3CX with HW phones (SPA941) in LAN without any problems. When I moved them to internet, I have been facing some problems related to NAT and STUN. After tuning configuration in phones and marking the extensions in 3CX as External I am able to call from these phones to PSTN via VOIP provider (which wasn't possible firstly). But I am unable to call from one to other. Also incoming callsi from external VOIP ends with no success. There are these lines Server status and call is not connected (no ring tone in headset during call, no ringing of called phone). 19:27:08.328 CallConf::Rejected Call (C:1A) is rejected: Destination is not answering 19:27:08.328 StratInOut:nCancel Call from Ext.201 to 102 has been terminated; reason: 19:26:52.875 CallConf:nIncoming Incoming call from Ext.201 to sip:firstname.lastname@example.org Any advices?