Actually, because its line of sight the transmitters not need be super powerful. I am an amateur radio operator and the sats i can talk to in LEO use like 100mW (0.1W) transmitters and we can pick them up. The biggest proble.m really is that the satellite needs a large antenna to pick up the phone. The higher the frequency they use the smaller the antennas on the sats can be.
Actually, because its line of sight the transmitters not need be super powerful. I am an amateur radio operator and the sats i can talk to in LEO use like 100mW (0.1W) transmitters and we can pick them up. The biggest proble.m really is that the satellite needs a large antenna to pick up the phone. The higher the frequency they use the smaller the antennas on the sats can be.