How do I enable “Do Not Disturb” and stop receiving all calls

Press the button beneath “More” on your deskphone screen.
At the Dialpad Features menu, Do Not Disturb should be highlighted in Blue. Click on the Checkmark button in the middle of the circular set of buttons above the number buttons.
In the Do Not Disturb menu, it will show whether DND is on or off. Press the appropriate button to turn it on or back off.
Press the back button if you need to return to a previous page or the Home button to return directly to the home screen.