Lapp.
You are incorrect. Even with the phone off, it can be activated by suitable equipment and the mic turned on. Someone can listen in to your conversation.
The only way to deactivate the phone is to take the battery out and this is an absolute fact! Google it if you don't believe me. Mobile phones are a tracking device off or on. Fact!
Of course not over the ocean but it was reported to be flying over land.
Pax families will have phone numbers.