At the moment - this *seems* to be working for us: 3CX v.10 w. SP6, default ports and STUN resolving. We're using the "PBX delivers audio" option. PA-2020 w. software v. 4.1.6, Application version 310-1401, Threat version 310-1401, Antivirus version 760-1045 Incomming NAT rules: Public ip on selected ports (port service) send to 3CX server Outgoing NAT rules: Internal IP to Public IP, Translated IP = Static IP, Bi-directional=no Rules: Allow STUN & RTP to outside from 3CX server Allow selected ports from outside to 3cx server Allow selected ports from 3cx server to outside Allow SIP from phones to 3cx (I'm not entirely sure if you need to allow rtp or selected ports from phones to 3cx server - at the moment it doesn't appear to be needed) Br Jørgen
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