I have 2 servers. My trunks try the first one, and then failover to the 2nd one as needed. So do the phones.
I would like to be able to put them individually into a maintenance mode for when I do updates and reboots so that calls won’t accidently be using them during that time. Is there a way to manually do that, so they won’t be accepting calls until I change them back? I don’t see anything about how to put them into maintenance mode.
Install a quick access list in your Internet router that blocks access to the server you are doing your maintenance on. The trunks will be unable to connect to it and will failover to the other server. Remove access list when you bring the server back online.
If you are doing this sort of thing you generally don’t want to cut off calls in progress, or cause them to misoperate, so you should be doing a shutdown gracefully on the Asterisk under maintenance. This isn’t perfect, because call pickup and adding to conference calls still won’t work.
The normal FreePBX apply config tries to keep all calls up, but I’d expect FreePBX updates applied to a shutdown Asterisk daemon would get implemented when it was restarted.