I'm also on the DNC - you're right, it doesn't help for sh*t. Filing complaints with the FCC & FTC don't help either. If you call them directly & ask what they're doing about the issue, their answer is "it helps us track these types of company's behavior & see if there's a pattern to the numbers they use". They aren't doing ANYTHING about this issue!
BTW - this was a robo call that actually left me a voicemail - "you may have won a FREE home security system!"