I've installed v3, and spent a few hours last night uninstalling and reinstalling it, each time getting different behaviour, it seems the latest behaviour has stuck for the last few installations: not working well with my grandstream ATA. I configured 3cx to send calls directly to extension 1 (ATA), no in or out sound to external call.. when I put an IVR in between, it works ok. Internal calls (between grandstream 486 ATA & Grandstream Budgetone) work ok. Calls are dropped apparently at random. problem with placing outbound calls (from either extension), depending on the number being called, either: I will hear ringing sound with external number never ringing, or Log message: "Can not resolve target for call from "Ext1"<sip:firstname.lastname@example.org;user=phone>;tag=6e8ee707a1880891 to <sip:email@example.com;user=phone>" or log message: "??: from 'SKSVR:0/MediaServer'ossible firewall problem. Address mapping failed on STUN server 188.8.131.52:3478 for local address ":9002"" or, I will hear nothing for a period of time until I am eventually disconnected.