You can choose to not receive incoming calls whilst still being able to use your extension to make calls. When enabled, callers are re-directed to your voicemail if on or otherwise hear busy tone.
You can also add a set of exception numbers for callers who are still be able to call you when you have do not disturb on.
To switch do not disturb on: Dial *08.
To switch it off: Dial *09.
To add a number to the exception list: Dial *10*N# where N is the number. That can include external numbers.
To delete a number from the exception list: Dial *11*N#.
