Sip 20 Error

Hello, every few weeks I stop receive incoming calls. Restarting FreePBX always fixes the problem. Please check out this picture for more information:
Picture with more info

Network Info
pfsense---->Netgear GS748TPS----->FreePBX
pfsense firewall stock.
Any ideas?

It seems to be a pfsense inssue. Whenever my IP address changes, the firewall states table does not update. Clearing the states table solves the problem. This is a known bug with pfsense see this:

Known Bug