From O2/Virgin:

"With the launch of O2 Satellite, now’s the perfect time to get your app fully ready for satellite connectivity. With a few small adjustments, it can stay usable even when customers have no traditional signal, keeping them connected when it matters most.

Enabling satellite support is simple. Most apps already work with minimal changes, as long as they handle low-bandwidth, intermittent connectivity. Once you've checked that your app behaves correctly in constrained network conditions, you can certify it using the official tools provided by Apple and Google.

If you need support, want help testing your app or would like to let us know it's satellite-ready, email us at O2SatelliteApp@virginmedia.co.uk"

Note, as yet I've not seen any facts about whether this service works at GA altitudes or for receivers moving at GA speeds.