Leave a message! Sometimes I don't pick up the phone because I am in the middle of something, and sometimes I can still see your phone number on caller ID. And sometimes I notice that you keep calling and hanging up without leaving a message (over and over). And one of these times, I am going to pick up the phone and ask you why you keep calling without leaving a message.
Look, I get that you want to talk to a person and not a machine. But if I answered every call that came through, I would not be able to get my job done. So call screening is something I have to do sometimes. Nothing personal. I'm not more important than you. I just happen to be in a job where I get tons of phone calls.
But don't keep calling back and hanging up. Your number may be listed, you may have already sent me something with your phone number on it. And when/if we speak, all I'm going to be thinking about is the fact that this is the person that called me seventeen times in a one-hour period.
This isn't intended as a rant, just a recommendation to think about it before you pick up the phone and keep calling.