Have you ever been stalked before or harassed?

I don’t know too much about the subject but I have had throughout my life various forms of stalking I did not find too threatening, apart from one incident when I had to go away for a few months. Mostly the type of stalking was “parked out side my apartment under a tree kind” or just simply the person would not leave me alone.
There are serious cases of stalking of course that go beyond what I have written above and are very dangerous. Someone’s comment got me thinking about it. So anyway that has not happened to me in a long while thank goodness.
But lately I am having prank calls on my cell phone, so I have changed my number. I just have a low tolerance to anything like that. Has any one else had this happen? From serious stalking where they felt threatened to someone calling you and using your name so obviously they know who you are but you don’t know who they are. What would you do about it?