This number has called me all day but left no message

Federal prison

Pretty sure this is correct

How did you find out it was a federal prison? I know someone in prison but not in D.C. When I called the number back it said the number was changed or disconnected?

Just got a call from this number myself. I didn't answer the first time as I don't answer numbers I don't know. However, it called back immediately. This is what my brother does when he calls. He is in a federal prison (although not in DC). I'm assuming they had to reroute the calls or something. But definitely a call from a federal prison.