On Mar 4, 4:37 pm, "Peter" wrote:
What is the maximum altitude (about) when the mobile phone becomes useless?
PeterK

I've had it ring at 2500'agl at which point I told whoever (my wife
and curtly too) that I was busy flying and then shut it off (I forgot
to shut it off prior to launch). If many consider it unsafe to drive
and talk, why do it in the air?