How exactly does that work? Cell phones have such small antennas and put out a relatively weak (and omnidirectional) signal. I think the phone would have trouble receiving the satellite's transmissions and vice versa.
Big antennas (25 square meters?) which are highly directional go along way to improve the link budget. The main lobe is focused on a pet small area of land. My guess is they will also use the lowest bitrate modulation/coding for additional improvement to the link budget. I think LTE goes down to QPSK 1/12, which supports demodulation down to about -7 SNR? Something around there.
Massive phased array that could potentially support multiple spot coverage. You still need a bunch of satellites to ensure continuous coverage unlike GEO birds that can cover a whole continent so it will be awhile until you can get worldwide (or nearly worldwide) coverage. With a really fancy DSP box and enough bandwidth, you can account for Doppler. The speeds won't be great but it will certainly be good enough for voice and SMS.
Adding things like mesh networks, you could drop a small server rack and generator at any where in the world and create a robust cell network to cover disaster zones.
