Yes. To block the calls coming from the PSTN side you can use the num-exp command. Say you wanted to block all calls going to 1408....... then you can add the following command
num-exp 1408....... 9408.......
If you don't have a VoIP dial-peer that only excepts 1+ or 011+ then it kills the call with a No Route to Destination.
If you us a gatekeeper for routing then blocking on the VoIP side is easy by putting a zone prefix gw-priority 0 in teh gatekeeper this will block VoIP patterns with the same message of No Route to Destination.