Phone usage, as evaluated in the OtoZen app's DriveScore, refers to instances where the driver physically interacts with the phone while driving at speeds of 20mph or more. This interaction involves lifting or moving the phone, causing the screen to unlock and turn on. Notably, phone usage doesn't include using the phone for map navigation if the maps were configured before the drive and the phone remains stationary. Additionally, handling calls via Bluetooth or car speakers or CarPlay, without physically handling the phone doesn't contribute to the phone usage score.