What is the Do Not Disturb feature? How can I enable or disable it?

When enabled, all of your calls will go to voicemail; if you are part of a department ring group, you will be skipped from the ring sequence. Please be aware that when you enable Do Not Disturb, there is no indicator on the desk phone display to let you know when it is enabled, so it can be easy to forget that it is enabled. If you are using the Dialpad app, there is a clear indication when you are in Do Not Disturb mode.

On the Polycom VVX-411 Desk Phone: Need to test this.
On the Polycom VVX-601 Desk Phone: Tap the More button on the touchscreen, then tap the On/Off slideswitch in the upper right corner.
On the Polycom VVX-250 or VVX-450 Desk Phones: Press the More softkey button, cursor down and select Do Not Disturb, then press the DND On softkey button. Press the Home button to return to the home screen.
In the Dialpad app on an iPhone: Tap the round icon in the upper left corner (typically the first letter of your name will be inside the circle) and then tap the Do Not Disturb slider switch.
In the Dialpad app on a laptop or desktop computer: Click the down-arrow in the far upper-right corner of the app and then click the Do Not Disturb slider switch.