Starlink sats have enough transmit power and receive gain to use normal cellular frequencies with a normal antenna on the phone side.
You might think it's a long way to space, but a few hundred kilometres of direct line of sight to your cellphone antenna isn't that much more to overcome compared to say, 25 km to a cell tower on the ground.
The biggest hurdle was getting a few thousand satellites into orbit so that coverage and availability is there.
Trying to, because there is no more money to continue development.
Hopefully they can pull it off and do the same as Pebble did when they released a last firmware update for their watches that allowed third party servers to be used.