Haha, yes I'm using OSSI to busy out the trunks already. As we understand it, Modular Messaging will still try to send MWI sets through the MAS and it will still do it if the trunk is busied out. So this left us with lights that were out of sync.
So for maintenance, we have to busy the trunks AND disable the ports. It'd be nice to do both tasks with 1 click since we have to do it a few times a month with Microsoft Patching.