Hi I have Freeswitch setup on a cloud server and Grandstream phones in the office connected successfully to the switch. I have never had any issues with NAT causing the phones or Freeswitch to lose their connection. The phones have "keep-alive" set so are always sending "OPTIONS" messages to Freeswitch to keep the ports open. I don't use the default 5060 port for the internal profile on the Freeswitch side. The office has a Fortigate firewall and a Opnsense box that is used to connect the office to a DC cloud server. The issue is that when a second call comes into the office, it will terminate after 32 seconds. There are only 2 voip lines so max 2 calls at a time. This only occurs if the second call is inbound. What is even more weird is that if the second call is answered by the phone that is already on a call, then this does not happen. If the second call is outbound, there is also no issue. I have done a sip trace and the calls progress correctly from CALL SETUP -> IN CALL -> COMPLETED. The logfile however has an ORIGINATOR_CANCEL message when the call is terminated. I have two phones at my house connected to the same PBX and when I use them to test, I cannot get the call to drop which suggest to me there is something in the office that is dropping packets but only on the second call. If the firewall was an issue, why would the first incoming call work and all outgoing calls work also? I have tried creating a rule on the firewall to allow all traffic from the Freeswitch IP but that make no difference. If the SIP trunk was the issue why would the home phones work. Can anyone give me some pointers on what I should be looking for in a SIP trace or tcpdump or loglfile or tea leaves? Thanks Dion.