I once sent a pitch to a former client. I hadn't worked for this client in several months, but she paid well and I was eager to get another piece of business. I was certain I had a proposal she would be interested in. But my contact didn't respond to my first email. Or my second one, a couple of weeks later, or my third, a couple of weeks after that.
We had a strong history together and I really wanted to work with her again.
And so, instead of my usual practice of giving up after a couple of tries, I kept at it. After yet another email went unanswered, I called her office and left a message. A week later, I left a message again. (I was feeling more and more like a stalker, but I really wanted the job.) A week after that, I called one more time--and she happened to pick up the phone. * Source