has called my cell 3 times over the past week, never leaves a message

It is a 'YOU WON' type of robocall.  If you press 1 to hear about your prize you are connected to a person.  They give you the option to press 2 to get them to stop calling.  I pressed 2.  We'll see.

Yep, just got a call (I missed it) but they did also did not leave a message. Got one last week also with a auto offer to press a number for a winning of a prize.

No message left, I am on the do not call list. Same day this number called another number also called, no message and that number is reported by many people as leaving no message or it hangs up if they do answer. There's a complaint section on the do not call site where you can report telemarketers that call you even though you're on the do not call list.