pfSense

The state killing in ppp-linkdown only kills the NAT states on the affected WAN. It leaves the firewall states there, which results in nothing with open firewall states working again until you manually clear the state table, at least in cases of things with long-lived persistent connections like VoIP.

Two issues here:
1) the state killing should obey the same checkbox for whether or not to kill states on gateway being down under System>Adv (<kill_states/>)
2) it should actually kill all the necessary states, even if that means wiping the entire state table if there are no other easy options for the time being.