Who called from 3143322970

Just called my work. Answered, no one on the other end. Tried to call it back to mess with whoever it is (it's very boring and slow here on Saturdays) but I keep getting a busy signal.

This no. called three times in three hrs. today.  They called yesterday and the day before.  Left no message and caller ID says St. Louis MO.

called 4 times today and keep hanging up .

i called the number back and it says
thank you for your call please press 1 to go on the do not call list, it may take up to 30 days to get you off the list,
i pressed 1.
it was very simple.