So, for years we've been using Nomorobo (not all phone companies are compatible) to intercept telemarketers. It works pretty good, catches about 90% and it's free. Your phone rings once then Nomorobo ends the call. They have a continually updated database they use to identify telemarketers but it has no way for you to white/black list numbers. I recently switched to the Jolly Roger Phone Company (not all phone companies are compatible), $6 a year for up to 3 lines. They take a different approach. Instead of cutting the call off, your phone rings once, then one of their many BOTS (computers) answer the call and attempt to engage the telemarketers wasting as much of their time as possible. After the call ends you receive an email allowing you to white list or black list the number and an audio copy of the call. Some are quite funny and some telemarketers are downright abusive.