Probably sales calls. I get the same thing on my phone which has the area code from when I lived in Cincinnati. They will use your area code to trick you into answering.
I nifty trick I learned from my CEO is to answer the call but don't speak and allow them to time out and hang up. This way your number becomes listed as inactive in their data base. If you don't answer or it gets your voice mail message, it remains active by default.