This number is evidently from Canada, or at least appears to be, so don't call back (it would be an international call).Caller has a heavy accent and says he is calling about a Windows Operating System upgrade or something about your computer.  4 calls today, and he has called periodically before.  I've previously told them not to call, and that we are on the "Do Not Call" list. I think its either a scam, or a telemarketer who just won't quit.  I found out how to block numbers on our phone, and I'm adding this number to the "blocked" list now.