I found something interesting. If I put my iPhone 4 in airplane mode, then turn it off, and turn it on, then go into settings and turn on Airplane mode, there is momentarily a "Carrier" menu there. The first time it vanished I didn't see what it was (I only noticed it because of something vanishing) so I tried again and managed to get into it. This is what it looks like: http://zorin.org/share/carrier.png Have I discovered some secret roaming setting? What is this menu used for? The fact that it vanishes almost immediately upon coming out of airplane mode after a phone restart must mean we're not intended to see it.