got a call, no message left

It's the free cruise survey scam.  Call back gets, "Thanks for calling.  The survey you were called for is now finished."    There is no survey just some nonsense questions.  You'll be offered a free something for completing the survey then asked for your credit card number.  It's a SCAM.  Block it. Here's a news report on it:
https://www.youtube.com/watch?v=I4tY1kz6lZ8
http://scam-detector.com/travel-scams/free-cruise

They are scammers. They called a number on the Do No Call list, I didn't answer. I blocked my number and returned the call to get a message saying that the survey I was called for has ended. I've gotten no less than 50 of the same type of call from different numbers - pretending to be a survey to get around calling numbers on the DNC list.
That in itself is an indication that they're disreputable. Other sites indicate they're offering vacation packages.