May be old but.
Best noticed comment of the day, “I switched my smart phone to Flight Mode and now I can’t find it”
I think Inmarsat is the inflight ISP via satellite the airine use, might also linked to the ADS-B and ACARS aboard. Even if the ADS-B and ACARS were off the plane’s main Internet gateway device, like route for inflight DHCP server, might handshaked to the uplink ISP, who knows. That’s my wild guess. Maybe they’d need the NSA to figure that.