I connect to the wifi at home and my dad always wants me to turn my iPhone to aeroplane mode at night. I didn't have it on one night, and he told me to turn it on and that he knew because he could "see it on the thing" and pointed to his phone?
How could he tell? Would this be a security issue? I'm on iiNet wifi
Read more: How can someone tell if you are on aeroplane mode?