Download and install

As is usually the case with any firmware upgrade that requires a computer, the upgrade to iPhone OS 4.0 can be a pretty laborious process.

This is because your iPhone 3G or 3GS needs to be backed up, the 800MB update downloaded and installed, then all of your data restored to the iPhone.

It’s a pretty simple process to download and install the update – you just need to plug your iPhone into your computer and iTunes will automatically detect an update. If it doesn’t identify an update, you can click on the Check for Update button in iTunes.

If you don’t already have iTunes 9.2, you will have to upgrade iTunes before you update the firmware on your iPhone.

Our firmware upgrade took around five hours on an iPhone 3GS using a MacBook, although we were attempting to upgrade just after the update was released and Apple’s servers were overloaded!

We recommend putting aside a minimum of an hour and a half to perform the upgrade and restore your iPhone to its content-loaded state.