Keep receiving calls from this number

I received a call from this number at 6:34pm today.  No answer when I picked up, then an automated "goodbye".  I called back, someone answered, said his name was "Roy" and wanted to know how I got his number. I told him that he called me, then he addressed me by name. I did not acknowdge that, and asked again who he was.  He said, well, actually it's about your security system.  I hung up.  Ver disturbing.I want to know why I am getting these calls when I am clearly on the do not call registry!

Trting to sell security.

Have received several calls but there is no response when I answer.  Suspect at best.

Don,t let him or whatever they are come around to your place. Id report it soon. I calculated 5 calls in february here. I will phone them back at some point.....I am Mad at this...

I received a call from this party this evening, said no need for another home security system I already have one, also own a gun and have a large dog.  Stop calling my number and hanging up, it's a pain in the a**.