O2 disappointed speed freaks ahead of the launch of the iPhone 5S and iPhone 5C by confirming that the phones wouldn’t be able to access its LTE network from Day One. That’s now been rectified, however, with the carrier pushing out an update to the iPhones that flips the 4G switch for everyone.
The process is pretty simple: you need only check for updates on your PC/Mac or directly through your iPhone. You should get a prompt for a new carrier settings file. After installing that, your brand new iPhone 5S or 5C will work splendidly with O2’s LTE. Easy peasy.