Many companies are seeking to do this, including the announced SpaceX/T-Mobile partnership:
Satellite companies are rushing to connect our phones and eliminate dead zones.
I understand how to receive weak signals at a great distance. But I am unclear on how satellites deal with having a large footprint vastly larger than a cell site, and hence, end up hearing a huge number of cellphone signals simultaneously. Yes, they can do spot beams – but even those, so far, have been very large.
Am interested to learn how they address this challenge. There are orders of magnitude more cellphones than Garmin InReach units, for comparison.