Sure,
You can either do one of the following options:
1. Create a translation rule on the gw to look at the ANI and translate it go to a number that does not exist.
2. Create a translation rule on CCM that does the same thing. You will need a CSS on the GW inbound and it would be best to have an inboundtranslation partition, inbndtrans-pt in it along with the other partitions that you want the gw to be able to get to like your allphones-pt.
If you have CCM 4.X then it would be fun to route that to a Route Pattern that you can have that blocks and the annunciator that says, STOP CALLING
HTH
Brian