As far as I'm aware all modern phones will at least partially wake up to sound an alarm even when turned off/
Does the iPhone/Android phones do this?
Does the iPhone/Android phones do this?
May be useful in business surroundings, but this makes the iPhone an awfully bad travel alarm.
If my Android phone is off, it's off. It doesn't turn itself on, period. If it's just idle, screen off, with lots of stuff asleep, sure it will "wake up" in that the screen turns on, and sound an alarm. But that's it.
This is done commonly by builtin services.