Originally Posted by JSanders
On Standby you will not get calls or messages. The unit is powered down, and will "awaken" only for alarm settings or an automatic ON setting.
On keyboard lock you will your phone calls and messages.
... I think this is NOT right, I put on stand by my phone and I'm able to receive calls/sms'/emails/everything, the difference is that when you lock the keyboard, you can press by accident the "Emergency Call" button and it will dial 911, and if you put it in Stand By, you will not press that button because the blackberry is just in stand by, with the screen torned off... I use the stand by option when carrying my 8100 in my pocket