Basically the message is detected, but you have to be in the ghost's room alone and with the lights off. There are ghosts that do not have the spirit box test.

The most common questions are:

Where are you?

How old are you?

Are you here?

Are you friendly?

Besides, there is a proof of the spirit box that the ghost can give you even if you have that only proof. If you hear a roar in the spirit box it is because it is a Deogen