This is what I've been told by our T-Mobile rep and why I recommend it to our top execs: 1) It is very secure and leaves no paper trail - it does not go through an Exchange server. In other words, if you do not want anyone at work to ever know about it you should send it via PIN. I'm sure there's a way one could hack in and see your PIN messages if they really wanted to, but it's better than SMS and email in these instances. 2) If we have a network outage at work, which we've had two in as many weeks, then no email. Everyone gets on their cells, traffic spikes, and you're lucky if you can make a call. PIN goes through without any hiccups.