In need of numbers?

It took me a while to figure out what this even was. So much potential…

A photograph of a beige control panel, attached to a wall. There's a grid of 5 × 6 buttons – except they're not buttons, they're just a mold where the buttons would be. Only the lower left of these 30 potential buttons is actually a button, and it's very lightly embossed with the word 'CALL'.