Yes, when the SHTF aircraft comms will work as designed, not even close to the same frequency bands, nor modulation techniques, nor power output levels. Not even a slight chance that cell phones will interfere.
In my minimal experience with airplane crashes[1], the aircraft's electrical system was kaput, and I relayed communications to/from ATC and Fire Dept. via ... wait for it, the pilot's personal cell phone.
[1] I ran an FBO at a tiny municipal airport during college (I re-fueled aircraft). I only participated in a few airplane crashes during my tenure there.