If you're talking about the DNC list (that's the only thing I can think of that you would 'enlist' in), one, that's not a call blocker and you've been putting yourself on and off the list by 'enlisting'. Once you're on the list, you're on it until you remove yourself from how I've read it. Or you could explain what you meant by 'enlisting'
When I answered the woman said my registration was chosen to be entered into the drawing for a $200 gift card if I took a survey. I asked to be removed from the list and we ended the conversation
I think this is a "Can you hear me now scam" that will get you to say "YES I can hear you" then use the "YES" in a totally different context to say you agreed to something and owe them money