Amateur radio operators with just a moderate bit of gain (small uda-yagi antenna or the like) uplink to LEO satellites with ~5 watts all the time. At peak power

Amateur radio operators with just a moderate bit of gain (small uda-yagi antenna or the like) uplink to LEO satellites with ~5 watts all the time. At peak power a cell phone can be about 3 watts... but their antennas are not directional. So that loss of ~8dB of antenna gain has to be made up by increasing the sensitivity or gain of the satellites in LEO by increasing antena aperture or better front end low noise amplifiers. It's all very feasible given the clear line of sight. What's less feasible is having enough of these at good positions overhead of a single cell phone to multi-laterate it's position using shared timestamps on the downlinked spectrum from multiple satellites. I think it's entirely feasible with the budget of a medium space services corporation that can launch 21 satellites.