How do you handle random calls from managers?

So I’m currently leaving my mostly in office job for 2 middle manager fully remote jobs, but I’m wondering how to navigate situations when you get random Teams calls outside of scheduled meetings while on another call with J2?

Additionally, am I hooped if meetings over lap? For example, weekly 1:1s or team meetings?

What have you guys said when in a corner like this? Better yet how do you avoid it? Otherwise I’m scared this will be short lived.

Thank you!