I moved across the country a few years ago and kept my old phone number. The only people that would have a good reason to call me from that area code are folks I already have in my phone. Every other number with that old area code? It's 99% spam; usually those "you selling your house?" scams, political scams. As soon as I see that old area code show up, I just decline or block.
Keeping your old number is a lot simpler, anyway, but this is a nice little bonus. #entertainment source