I am getting unwanted calls from this number.  They are apparently looking for the person who had this number before me.  Take my number off their list. I have called and no one answers

I get 10 or more unwanted calls from this phone number daily. When I call it back it goes to a recording that states Ext. 501 is not answering, please leave message. Cannot get anyone to answer the phone. Take my number off their list and DO NOT CALL ME ANYMORE

This number calls me 4 times a day you cant call it back and when you answer it no one says anything! How do i make them stop!!

This number is continually calling my cell phone.  when I call back, no one answers.  I would like to be removed from this number's list if at all possible.