So if you open Profiles and scroll all the way down -- below loud, vibrate, quiet, normal, phone only, and off -- there's no Advanced option at the very end?
I'm sorry I can't be of more help. That is the only way I know of to change this. You could try talking to your IT person at work, or maybe someone else here in the forum knows why you wouldn't have this option. ¡Buena suerte!
Edited to add:
Maybe this will help ... It says go into Ringtones/Alerts, then Messages.