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. It may take a few weeks to notice a difference, but I've been doing this for about 2 years now and I've experienced a tremendous reduction in telemarketing calls. By the way, the "Do not call" registry is only for bona-fide telemarketers and has no bearing on scam telemarketers. The scammers find all kinds of ways around it. And if you call back or press some number they say to be removed from their calling list, you are only verifying that your number is valid and it will get sold to every scam telemarketer on the planet.