When gateways unregister due to various network blips or maintenance, it can cause a PLAT-ALM in your Communication Manager. These will linger forever until you clear them, It’s very simple but you don’t do it from SAT, you do it right from the shell. To see all of the alarms, login to CM’s shell and type

almdisplay -v

To clear them all, just type

almclear -a

If you still have a problem, the alarm will re-propagate so I haven’t seen the downside.