Not sure how it works either but I do know that as far back as 9/11 passengers were able to call on their cell phones to folks on the ground. It’s why Flight 93 decided to take on their attackers - they called folks on the ground and heard about the attacks on the Pentagon, NYC.
Thank you for the information on cell phones. I never knew that.
Just for the heck of it I might try sending a text sometime from an airplane.