Hi,
I see two possibilities, one, configure dial-peer with "answer-address" to route the calling numbers to a message, the other, have a TCL IVR script to the same effect.
However, I think in both cases the call will be answered, even if that may not be desired.
Now that i think about it, if you configure multiple dial-peer with "answer-address" you can have more than one translation-profile associated to it, hence more than 15 numbers. I haven't tried this personally.
Does this helps? If so please rate post using the scrollbox below!