Answered the phone and they just hung-up.  Tried to call them back and received a busy signal.  

Same here, with the first call on 1/12/15.
On 1/13/15, I received a call from the same number - asking for a person I know but who has nothing to do with my number.

Called yesterday and today
Never leave a message

Received a call from this number, woman said she was from the department of the U.S. and had a very strong foreign accent.  When I asked what Department, she became confused about my question so at that point I got very rude and told her her scam was not going to work and hung up.

Got a call from this number day. They asked my name. I said yes. then they hung up. Tried calling back but just got a busy signal. I pray it wasnt a scam.