A constellation for SMS-like service need not be as large as a constellation designed for general purpose internet or telephony. The former just requires one (or a small number) of satellites in a Sun-synchronous orbit while the latter may require a large number of satellites in a variety of inclination and "orbital planes".
ronaldoCR|3 years ago
basementcat|3 years ago
https://en.m.wikipedia.org/wiki/Sun-synchronous_orbit