Hi All, I've been using 3CX v10 with a Zywall USG-200 now for some months and it has been rock solid and reliable. We were taken over by another company recently and the USG-200 has been replaced by a Checkpoint UTM-1 device which I no longer have control over. What I have noticed is that after 30 seconds calls are dropped after and ACK error. 14:49:40.161|.\InviteADS.cpp(545)|Log2||InviteADS:nAckNotReceived:[CM503021]: Call(2): ACK is not received<br> I then ran the firewall checker and it looks like there are translation errors. Looking at some other posts on this forum it seems that the firewall is obviously mis-configured and probably a PAT/NAT issue. Does anybody have any pointers on settings for a Checkpoint UTM-1 so that I can direct these guys in the right direction.