If you want your phone to enter the Do Not Disturb Mode, you can switch it on by using the DND button on the phone.
PLEASE NOTE THAT WHEN ACTIVATED, DND WILL BLOCK ALL CALLS TO THAT PHONE.
When you activate the DND, most of the phones will display an DND icon:
CORDLESS Phone (DECT)
1. Enter the main menu
2. Search for the DND option
3. Save the configuration