You need caller ID for a blocker to work. Try Amazon.com for a wide variety of available blockers. My CPR blocker allows one ring and then dumps the call.
Just called. Someone with a VERY ghetto accent (woman) kept asking me for my name. I answered because it is a local area code. I have health issues, and I never know if its a doc trying to get in touch with me. I asked for her name....she kept mumbling and/or the phone cut out. She mispronounced my name and asked me to verify, I hung up and blocked the call. I'm not telling some random ghetto b**** who calls me and demands my info what my name is....people are incredibly stupid nowadays if they give people like that their information for ANY reason.