This might be a daft one, but I've not seen an answer on this yet. If the iPhone 4S has no option to switch off 3G, does that mean it can only use 3G for calls also? What would happen if I tried to make a call/text in an area with no signal? Or is the ability to fall back to 2G/GSM still there? The lack of an option to switch off 3G in preferences concerns me.