I used to be in the telemarketing business, and we always showed up as an unknown caller, I think it was because our phones were on a t1 system or something. At any rate, you can get put on both your state and national do not call list, and if telemarketing companies don’t adhere to your request, they stand to get fined $10K a pop. Once your on those lists, if you continue to get calls I would play the game and extract as much info as you could, then report them. Telemarketing companies take do not call lists seriously and they will honor your request, it just might take a little time for all of the telemarketing companies to purge their new list. Until then, just pick up the phone and say FFFFFFFFFFFFFFFFFFFFFF U. Just like that. BTW, I don’t think you can’t block an unknown number, its like trying to get taken off a junk mail list that has no return address. But technology may have changed quite a bit since I was in the game.