I created a contact in my phone called "DNA-solicitor", and have added this number and about 20 others to it. In the Contacts settings of my Android phone, I have it set to send calls from "DNA-solicitor" straight to voicemail. My phone won't even ring for these fools!
Just wanted to share that tip... they reach me ONCE, then they're added to that contact in my phone, and shall never reach me again!