If you are meaning the red phone button, I don't think that is an available option. Depending on your model, there is a "convenience" key either on the left side or in the center between the phone keys (on older models with no trackball). This key can be reprogrammed in Options/ Screen-Keyboard. On some models, holding in the mute button on the top of the device when there is no phone call in progress witll put the device into standby mode (on some models this will just put the ringer into vibrate mode).
posted by DigitalFrog ________________________________ WARNING: May contain traces of nuts.