Thanks. IIRC, when this program started, CBP had a special wifi network that you had to connect to in order to securely upload your information. I guess that is no longer the case.

I foolishly forgot to switch back to my T-Mobile SIM while on the in-bound flight, and I didn't want to bother trying to swap cards in the hallway. Global Entry had no lines, and it was just as easy*.

* - lesson learned: when traveling as a family, make sure everyone is out of sight of the camera after each receipt is printed. The kiosk won't let you process another passport until it sees no one standing in front of the kiosk. The only bummer is that we had to declare food since it's asked on the GE kiosk and not on the app.