Check/Report uptime or last boot?

[jolouis]

OK silly question but since you can see the issue from the PBX side, why would you not a) try to find out what is actually causing the loss of registrations and fix that and b) monitor from the PBX side (which is what matters really anyway).

i.e. have a task that runs on the PBX checking for phones that the system marks as switching from registered to unregistered. Then, catch any where that happens, run a ping test to see if the phone is still alive, and if it is then either push a re-registration request or push the reboot.

Have your script/monitoring keep track, and any phone that it tries to fix as above but does not see come back online after say 5-10 minutes, then send you a notification to manually intervene...

That would be my logic anyway as you don't really care about uptimes of the phones, you care about whether they are staying online or loosing connection and not working.