Several calls a day to my company cel phone. Who is this and what do they want?

This number calls every day and never leaves a message and they hang up if you answer.  Most annoying

called me 3 times today

This number calls multiple times and never leaves message and have read people call back and gives a "do not call" option.  Never do this as it is part of the scam and invites more problems

Have been receiving Calls three four times a day, many times in the night hours since last one month. very annoying.some times with block ID.