Fix for Apple’s iOS 8.0.1 updateSeptember 25, 2014
If you’re one of the unlucky people that updated your shiny new iPhone 6 or 6+ yesterday only to find it could no longer make calls (among other less important things) here’s what you can do to downgrade back to the original version of iOS 8 released a week ago which seems to be the only “solution” until Apple comes up with a fix to the buggy update.
Things you’ll need: Your broken iPhone, a PC or Mac with iTunes installed, a Lightning to USB cable, and an internet connection.
Step 2. While that’s downloading, go to Settings > iCloud > Find My iPhone on your iPhone and turn the service off. You’ll need to enter your Apple ID and password to do this.
Step 3. Fire up iTunes with your iPhone plugged in, then click on the “iPhone” from the source menu on the top right.
Step 4. Click the “Check for Update” button while holding Option (on a Mac) or Control (for Windows users) key.
It will pop up with a file menu where you pick the firmware (which will be one of the two .ipsw files you downloaded above), then hit OK.
Your phone will proceed to install iOS 8.0 as an “upgrade,” but won’t actually change any of your settings or affect your data. Checking the iOS about menu once it’s done will also confirm that you’re actually running iOS 8.0, and not 8.0.1.
If you’re having issues getting the install to start, one option is to do a full restore, which requires setting your iPhone into recovery mode. It also means restoring from a backup, which could be a problem if you’re trying to restore from a backup of 8.0.1 on a phone running 8.0. If you can wait, it might be worth seeing if Apple pushes out an update for the update sometime later today. For everyone else, enjoy making phone calls again — on your phone.