If some of your friends are in MLM, then you will know it.
Otherwise, it could be some competition you participated and your
number was shared.
If he calls again, just ask where he got your number. Tell him
don't say some company policy don't allow him to say. If he asks if
you want to meet, agree that you meet him and make a fool out of
him. I did that, and those MLM never contacted me again.