I don't think they buy new phones...it wouldn't be cost-effective. They're crooks so it's more beneficial for them to have the equipment to "piggyback" off disconnected numbers and go "fishing" for their next "victim"!!! There's no additional cost to doing it this way...
And you're right...IT'S NOT NECESSARILY A LOCAL CALL just because the phone number is! They've decided that people are starting to ignore or monitor "800" numbers and have decided to use local numbers. EVERY TIME I get a "local" number that I don't recognize I call it from a landline WHILE MY CELL PHONE IS STILL RINGING and MOST of the time it's DISCONNECTED...IMAGINE THAT!!!
It's a never-ending battle to ignore these calls and there really isn't anything that can be done about it since the numbers are disconnected. The scammers probably use it once and then use another number...then they probably recycle them and start down the list again!
They SAY they are a general contractor because Blue Cross is such a recognized name but I'd bet the rest of my life's earnings they're the same scammers using every other method out there to scam unsuspecting people!!!