Activating Do Not Disturb

If you have been given the ability to place your phone in DND, press the DND button. Do not lift handset. DND button lights steady.

Removing Do Not Disturb

1. Remain On-hook
2. Press DND button
3. The button LED extinguishes

I'm thinking that if other phones have a DSS/BLF programmed of that phone in DND---the LED lights steady. When you call an extension in DND, I think you get a "fast busy".