Question about Netgear AirCard 790

I have just tested it. You do not have to select the carrier that the card dials in to as the APN, but you must create one for knowroaming. APN: knowroaming otherwise everything empty. Then it works immediately.

I cannot say whether and how it works with the data packages (Unlimited Data). But I think that you first have to order this on the iPhone via the app and then restart the modem. Then it should possibly work.

I have no experience with knowroaming so far. I had a SIM card from PrepaidZero (MFi/Tablet/Hotspot plan) on our last major trip and had no problems with it.
So I would potentially conclude that the normal SIM card (not the sticker) from knowroaming should work (no guarantee of course ;) ).