I discovered today that FaceTime didn’t work on my iPhone 4: people couldn’t start FaceTime calls with me and I didn’t have any of the FaceTime buttons present. Turns out that this problem is caused when restoring from an iPhone 3G running iOS 4 — it seems the FaceTime on/off setting is imported from the iPhone 3G (which has it turned off as it doesn’t support FaceTime). Going into Settings > Phone and then flipping FaceTime on solved it for me.

Other people seem to have had to jump through a couple of extra hoops to get this to work, if flipping the switch didn’t get you going, take a look at this post over at the Rusty Brick blog.

Update 2010-08-22: Still having trouble? Did you jailbreak your iPhone 4? There’s something else that might stop this working too.

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