I have a system that keeps randomly rejecting sip trunk calls after the system has been running for a few days. They get hundreds of calls a day but after a few days certain calls get rejected but not all. I upgraded to the latest build of version 10 10.1.0.8.0 build 3. I have upgraded the firmware on the firewall. I have tried multiple changes to the sip trunk settings. The firewall is locked down to allow only the SIP provider to connect so I know it is not hackers taking down the the trunk and I have turned on all monitoring of the system and I am not getting failed logins like I get if I open the firewall ports to anywhere. Rebooting the system fixes the issue. I have now found that if I select the sip line and uncheck the in service button save config and then recheck the in service box it fixes the problem. At least I don't have to reboot the system so this make fixing it much faster. This makes it look like a phone system problem as this always fixes the sip trunk connections and I can get hundreds of calls a day again for a few days before we randomly get Unavailable - No trunk or registration errors. I have older version 9.1 system that work fine and newer version 11. I am thinking I need to upgrade the system to 11.1 but wanted to see if anyone else has seen issues with version 10.1 and sip trunks or any version with similar results before purchasing upgrade.