I think that (please correct me if I'm wrong) the decision to ban phones in-flight is largely to ensure peace in the cabin, as opposed to avoiding interference with aircraft systems.
Please excuse me, I don't feel well today, so my brain is not fully functional.
However, I do recall learning that mobile phones are banned because they can interfere with signals used for navigation, for example the ILS signal. The theory is not simple if I remember correctly, but that is the reason.
I don't think the measure is there just to keep the cabin peaceful.
