Looked at from the mobile phone network aspects.
When on the ground the cellphone will be able to communicate with say 3 or 4 base stations, and will hunt around looking for the best signal.
In the air the phone will be in range of 30? base stations and will still hunt around for the best signal. This may cause extra work on the network control computers, and if lots of people did this at one time the system would overload, and possibly crash?
I am aware of one person who 3 years ago was cautioned by the mobile phone company after tracking the A1 at 100 plus knots for several miles. I think they used the phrase abusing the system.