A phone has mobile data turned off.
No wifi antennae is connected. We were in the wood, on the hill, minimally 3 km from the nearest village. The nearest, higher hill, has a mobile antennae. So, the mobile signal was on. Even if there was a wifi antennae, I hadn't connected to it.
So, obviously, no Internet connection was active.
But the phone suddenly decided to update the Android OS. And started to download the update. It was even finished - in 5 hours - without internet being on. How could it be downloaded? Will I have to pay for those data? (the phone has no prepaid Internet)
The device is ASUS ZenFone 3 Max.