Except those specifically allowed by FCC or FAA, all PEDs have to be be tested and proven safe by the manufacturer. In case of medical PEDs, the guidance is that the airline is responsible for ensuring any PEDs it allows are not going to cause interference with aircraft systems and, it may not disallow use of medical PEds unless the PED is unsafe. Some CPAPs now carry a label that they meet the EMI specifications. The testing has to be done by the manufacturer and the data is evaluated by the airline. For a PED like a cell phone the situation is even more muddled. Even if a manufacturer conducts sufficient testing and the airline deems it EMI safe based on evaluation of the data submitted by the manufacturer, FCC still does not allow cell phones, neither does FAA. There is no reason for anyone, the manufacturer or the airlines to make the first move. If demand/pressure for allowing use of cell phone grows, the situation might change. I don;t see it happening anytime soon though. IMO until anamolies cases of suspected EMI have been resolved, I don't think anyone will say definitively that it's OK to allow use of cell phones.