Being a 7030 I would upgrade to at least 4.93 just to avoid the file system corruption issue.

Also unless the isp equipment is battery backed up your alarm system won't be able to callout when there is a power outage.

Have you tried changing the po rd ts to normal them back to cid trunks?

When you call in is there a couple of second pause before the handsets ring?

Eg

Burst of ring, pause, handsets ringing.