Hi,

a 30s delay (more exactly, 32s) is for sure a nat issue: you are not receiving the final ACK.

Check if there is a SIP ALG enabled on your SonicWall and try to disable it.

Best Regards,
-- 
Vallimamod Abdullah
SIP Solutions
vma@sip.solutions
linkedin.com/in/vallimamod
.


On 10 May 2019, at 16:10, Sean Devoy <sdevoy@bizfocused.com> wrote:

Hi all,
 
I have a problem with one client where the call is fine and they can talk for almost exactly 30 seconds, then the log says originating phone (of FS) hung up.  This only happens like 1% to 5% of the time.
 
The phones are Mitel 6867i and 6865i which must use TCP not UDP.  The firewall is a $#!#&* SonicWall.  I am 99% convinced it is the firewall.  It happened once on a Cisco phone using UDP so I increased the firewall UDP timeout.  I already have keep-alive set to 30 seconds.  It has not recurred on UDP phones since.
 
Any ideas on something to do to Mitel config or SonicWall that might prevent a drop after 30 seconds? 
 
I have considered PCAP, but with so few occurrences I am worried about PCAP size before I get a “hit.”
 
Thanks,
Sean