Saw the number on my Caller ID

A man rang my phone and hang up. When I called back he said he was coming to my country and needed a friend as he knew nobody here.

I saw the missed call and called back when a man answered and told me he was coming to my country and needed a friend because he knows no-one here. I asked him how he got my number and he told me he made it up and just dialed. He went on to say he is a doctor who is single, is 30 years old and looking for a girlfriend.

I got the same call from a man named Ricardo who says he will be visiting Jamaica and has no friends.  I immediately ended the call.

How do these people get my number?