I realize this post is a few years old, so I'm hoping you found a solution! We're struggling with many fire alarms in our migration from Avaya to Cisco using VG350s. Currently troubleshooting a set of Silent Knight panels, Model SK-5208.
Alarm > VG350 > SCCP > CUCM > MGCP > 2911 > PSTN.
Not sure how closely that matches your setup. Any advice is appreciated.