Most obviously, you’ll see a large dark grey notification on the lock screen. This will also tell you how long the mode will be on for. If there’s room for it (the X- and 11-series handsets don’t, because of the notch), a faint little crescent-moon icon will appear in the top bar on your iPhone or iPad’s screen.
When you call a dead phone does it ring?
Answer: A: With a dead battery it should not ring but it should go to voicemail directly.