Called my cell phone but didn't leave a message. I called back and a computer voice told me that I won a $100 reward card. I hung up after it said that.

It's obviously a phishing attempt.

same as mitchell.obvious scam

Yesterday they called twice, but left no message. I moved the number to my Reject List...I'm done with them!!!!

Got a call from this number, partway into the robo-call about 'You've won...' recorded message cut off and was replaced by heavily accented voice asking for birthdate. Hung up on them.