I worked in software in a domain vaguely related to ATC, and I've heard a few years ago that even sampling the voice commands (and routing them as VoIP) is prob

I worked in software in a domain vaguely related to ATC, and I've heard a few years ago that even sampling the voice commands (and routing them as VoIP) is problematic , as altering the signal through sampling and encoding can go against regulations. I don't remember the details though. It was in a project related to ATC and area control / FIR services backup systems.