Afterall, text messages etc. don't need much of a signal for long to work.
mixture, yes that occurred to me too.
Doing a bit of Googling, I stumbled upon these two interesting papers that are pertinent to this subject:
Airborne Cell Phone Performance
Electromagnetic interference with aircraft systems
I suppose I should sometime, just in case it's important one day.
FOR,
Based on my experience in Canada and New Zealand, there is an expectation by ATC that pilots will use mobile phones in the event of comms failure. I wonder how well that works in practice?