Getting off of Memphis cold call lists as an owner?

[Chad Wilson]

Hello,

I have owned a SFR in Memphis since May of 2012. I have always received the occasional cold call, but in the past few months it has gotten out of hand to the tune of about 4 or 5 a day with Tuesday and Thursday being the busiest. What can an owner do to get these people to stop calling? I have texted some of the more aggressive (3 to 4 calls on the same day, no voicemail...) ones asking for them to stop but week after week it is the same. Would I be better off just changing the number with the city and county to some unmonitored Google voice box? What do you all do?
 
P.S. yes all of my numbers are registered on the National Do Not Call registry.