[Freeswitch-users] Second incoming call terminates after 32 seconds

[Dion Phillips]

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.