You people can press one all day long but you are not being placed on anybody's do not call list. These people are illegally operating a scam. What they are doing is against the law and they are not kindly offering you some way to get off their list. You're on their list and there's no way in the world you're getting off of it.
Sure there is, it just depends on if you're able to let your phone ring clear through with no kind of answer. You'll probably never get rid of them entirely, but you can definitely start making pests' 'no call lists' by not answering mystery numbers in any way.