I still have a land line and use Nomorobo to great success on that, free service we got on the internet years ago. We screen our calls and don't answer numbers we don't recognize. With Nomo a live person has to press a button to put the call through, so most calls ring once and then go away. The caller name also flashes on our tv as well as on the handset. If they get through I report the numbers.
FYI -- don't ever call them back or bother to ask to be removed from their service. Chances are that is a random dialing program (no list) and being removed from their service doesn't prevent them from selling your number to another company (often under the same roof) as a live number.
My cell phone though... I get more fake calls and calls for the previous owner (I've had this number for 3-5 years now...) than I do for myself and Nomo is a pay service for cell phones. Didn't they used to have an option to ignore particular numbers with a button push?? I guess it's enough of a problem that they have the pay services and the cell companies don't want to deal with them. Anyway, I never offer up my cell number to businesses in any way, so no, I didn't enter your contest so I couldn't have won whatever it is.