Assuming GV is defined on SP1.
Use OBi Expert to make following change.
Voice Services -> SP1 Service -> X_InboundCallRoute:
{(+1NPA(1111111|2222222|3333333)):ph},{(+1NPAxxxxxxx):},{ph}
{(+1AreaCode-NPA(1111|2222|3333)):ph},{(+1AreaCode-NPAxxxx):},{ph}
Replace AreaCode-NPA with your number.
Replace 1111, 2222 and 3333 with numbers within your NPA you want to ring your phone. If you need more just add |4444
All other numbers within your NPA will be routed to nowhere.
GV sends an 11 digit callerid with a plus sign prefix. That's why the "+".
Edit:
The blocked numbers should go to your GV VM. I would test this.