Without looking at how it fits into the privacy ideal, you could try TrueCaller. You can block by....
any number of sequential digits in the number which is great if they are using blocks of numbers.
..block all hidden / withheld numbers
.. Block those not in your contact list
..block specific numbers
Blocking can be....
It rings on their side but not yours.
It goes to voicemail
Rejected.
It will also display the name associated with that number if it is held on its system. This is business names only, and is mainly customer updated