In naval ships, there are typically announcing circuits. They’re loudspeakers that broadcast in particular areas, which allow you to make, say, announcements to the engineers about engineering events or equipment or whatnot, without having that announcement go through the entire ship. Of course, there is always the “1MC” (master circuit) that goes throughout the whole ship.
Here is my headcannon list of announcing circuits in Unreliable. (Which I needed for my fic.)
1MC – shipwide
18MC – navigation room local
JA – Captain’s Quarters
54MC – all crew
X3JZ — SAM
X4JZ— Felix
4JZ — Parvati
X5JZ — Ellie
X6JZ — Max
X7JZ — Nyoka
JS – Galley
26MC – Engine room
39MC – Cargo room
75MC – Head