Who called from 4042671839

I've been getting this unknown number. Could be political robo calls.

They called. I didn't answer. They left no message.

Same as everyone else.  Calls.  730 pm Saturday night to a NO CALL number we have.  No respect for DO NOT CALL LIST.  So, I monitor the message after our Greeting plays, and like everyone else, whatever their purpose - no message left.  Just call us, and listen to Greeting, and just simply hang-up.  Why the heck, call ?