Restoring an iPhone from an iCloud Backup can only be accomplished during the initial setup of the device and requires the handset be connected to a Wi-Fi network.
Tap and slide the arrow icon to unlock the screen.
Tap the preferred language.
Tap the preferred country or region.
Tap the desired Wi-Fi network.
Enter the network Password if required.
Tap the desired Location Services option..
Tap Restore from iCloud Backup.
Note: If the handset was activated via iTunes or Cellular Network, a prompt to connect to a Wi-Fi network will appear. Tap OK and follow the prompts to connect to a Wi-Fi network and complete the restore via iCloud.
Enter the Apple ID and Password.
Read the Terms and Conditions and tap Agree.
Tap the desired backup to be restored.
Once the restore is complete, the handset will restart.
Tap to slide and unlock the handset.
Note: If prompted, enter the FaceTime Password and tap Log In.
If prompted, enter the iMessage Password and tap Log In.
The iPhone is now restored.