Originally Posted by
Pontius
Well, I say none of the four commercial types (Boeing) I've flown can SELCAL another. You may have an app installed on your phone and you may have access to the internet in flight; well done you. Normal pilots do not have a SELCAL app on their phone and not so many have internet access, so your solution is crucially flawed.
Sigh. Thank goodness for microphones.
https://en.wikipedia.org/wiki/Phreaking