"I have opted out of their call list" Don't tell me let me guess, you pushed a number? In our experience that gets you many more calls since you have just verified they have a live number that someone will answer.
This phone number (470)204-6827 is probably SCAMMERS!!!! I will be calling the Federal Trade Center and reporting them. I'm glad with my phone I don't have any voice mail set up so they can't leave me a message anyway. I'm glad I can decline any unwanted phone calls.