I have a friend who is a pilot for American. He tells me that pilots use their cellphones all the time during flight.
Also, look around the airport, there are always wireless towers, otherwise you wouldn’t get service in the airport.
IMO, the no cellphone rule on airplanes has always been about reducing passenger complaints. Who would want to be on an airplane with 300 people talking on their cellphone?
The problem is having the call picked up by multiple non-adjacent towers ,, it screws up the billing ..
I have never heard this from my husband in all the years he’s been in the cockpit. Not even once. I’ll ask him though, when he lands.