This number called. I didn't pick it up. They didn't leave a message.

The area code and first three digits after the area code are the same as mine. I have noticed recently that I am getting many calls from phones that start with these same numbers. Makes it look like it may be a call from someone I know even though they're not already in my address book. But when I Google these numbers (like I do with most calls I receive from unknown callers) they aren't listed. What's up with that?