I've noticed that when I call my boss' ext 2504 and he's on the phone my display then shows his rollover, 4504,(it shows 2504 2504 BUSY) which tells me he's on his PDN 2504. But some phones don't show this, even if the person I'm calling is on the phone. What is the CLS parameter i need to set/change so that I can see when their PDN is in use?