Who called from 3123527122

3 times today - No one there when I answer

just called and no one was there when I answered

This caller has made numerous calls to my cell phone.  Who is it?

Continues to call and leaves no message

They have called me 8 times today alone starting at 9:07 am. It must be someone selling something. I called twice and got a recording saying, "The number you dialed is not a working number." If this is the case how do they keep calling me?