The old analog & digital technology did fall over if many cell registrations were attempted from a signal mobile, such as from an aircraft where the phone can receive many base stations due to its height - it was designed as a ground based communications system. However, the whole question needs to consider that the AC is generally a well designed and maintained bit of kit. The phone is mass produced to the cheapest price and is more likely to emit spurious signals than an AC. If things do go wrong, the AC problem is more likely to be picked up at the appropriate maintenance period. When was the last time you had your mobile phoned checked/serviced? And even if you have, I would guess price was a driving force in the job, and not standards. If you want to prevent the possibility of an accident due to radio interference, mobiles need to be off (or in flight mode) during flight. Taking a domestic piece of kit into a professional AC and *never* expecting interference is "pie in the sky" - unless its in flight mode. If you wanted to test every phone ever produced against every AC ever produced, to see if they interfer, you could. However, it would be prohibativly expensive. Much safer/cheaper to require all mobiles be turned off.