Called my cell and did not leave a message, the caller id was blank except for California.

I answered this call because I thought it was one of my teachers.  It is a recording which states that they are calling in regard to my credit card account.  Then they say, there is currently nothing wrong with your credit card account, (I know that) but is is URGENT that I respond immediately to lower my interest.  I hung up at this time.  So infuriating!  Just block it.  If you try to call back, you'll just get a busy signal.

Called my cell and did not leave a message, the caller id was blank except for California. I'm on the do NOT call list, why are they still calling !!!!!!!!!!!! BLOCKED  

Called my cell. I answered and no one responded. They hung up after a few seconds.

Just called me, no message left. Tried to call back and its busy tone.