How about having the SM’s automatically reboot after 10mins of not being associated with an AU. We had interference that knocked out most SM on one sector. About 50% came back after the interference was corrected, the rest needed a call to the customer to tell them to unplug the SM and plug it back in again. The tech support guy said he sees that from time to time.
What software are you running? We had a major issue with 8.2.2 where the subsribers would lose registration but thought they were still registered so they never attempted to re-register. We were rebooting SM’s like crazy until we upgraded to 8.2.4. Problem completely went away.