This number  called  3 times today no voice . Is the  caller flashing or what?

They called me, it was a robot, they hung up on me as I was trying to get removed from the calling list.  I called the number back, it said all agents were busy and to please hold, I held for about 30 seconds before it hung up on me.  Then I called back and it keeps saying it's closed and to call back between 10am to 8pm eastern.  But this was 1pm eastern when I was calling.

keep getting calls from 2544476501 and they are not leaving any voice mail... calling even on sunday mornings or late at night