When I get a call from a number I don't recognize I lift the handset (or press the speakerphone button) and immediately press and hold down the # button for about 30 seconds. If it's a robo-all, it will delete my number from the calling list thinking it's a bad number. If it's a real person, they will hang up and delete the number from the call list for the same reason. I used to get a couple dozen of these calls a day from various telemarketers. Now I get 2 or 3 a day so this must be helping. I agree with another poster here that our phone companies only allow 30 blocked numbers and that list fills up quickly. Try the # button method and see if it doesn't reduce the number of crap calls you get each day. It may take a few weeks to notice a difference, but I've been doing this for about 2 years now and my number is definitely getting sold to fewer and fewer telemarketers, that's for sure.