iPhone X: How to tell if Do Not Disturb mode is turned on
Without a constant icon at the top of your screen, it's not always apparent if DND is enabled.
With the iPhone X and its notch taking up a good portion of the status bar along the top of the display, Apple had to move some indicators to Control Center.
For example, you can no longer display the battery percentage on the iPhone X's status bar. Instead, you need to swipe down from the top of the screen to view Control Center to check the current battery percentage.
The same is true for the iPhone X's Do Not Disturb mode. Instead of having a half-moon in the status bar as other iPhones do, the DND indicator is nowhere to be found on the main screen when enabled.
You'll need to swipe down from the top right corner of the screen, where Control Center is activated, and view the DND shortcut button to see if it's enabled. If the icon is purple, DND is turned on. Otherwise, DND is disabled and you should receive alerts as you normally do.
Recently I enabled DND on my iPhone X when watching a movie, only to forget it was turned on after I left. It wasn't until a few hours later after missed calls and messages that I realized it was still turned on, despite using my phone several times.
