If 47-12 is set to undefined then it does nothing. If it is set to function on a day or range of days, then during that time it goes to, in your case routing mailbox 1. all other times and days it looks at the setting in 47-11 - default mailbox (right side of the screen). At a station allowed administrator rights, press VM button, dial 74 + 4 + 001 to hear greetings in box 1 (001).
Routing mailboxes and station mailboxes are not the same.