Your cell phone switches towers all the time while you're on the road. My cellphone (republic) switches from WiFi to cellular network mid-call if I'm on it when I leave a building. This is not a new problem.
The hard part here is that you have to target the beam at the satellite. It's not a wide angle beam that's used it's a focused beam. (This might not be true based on what they implement)
But for Geo it's a targeted beam. So this isn't a perfect corollary, and my example was pretty bad lol.
Damn, I guess we ran out of interesting problems to solve then /s.
Networking technology switching is unrelated to a call, which always uses cellular.
I've been using them for years and it works fine.