Unlocking an iPhone: Do You Have to Restore?

When you unlock an iPhone, the official instructions say something a little odd:

If you have a SIM card from a carrier other than your current carrier, follow these steps:

  1. Remove your SIM card and insert the new SIM card.
  2. Complete the setup process.

If you don’t have another SIM card you can use, follow these steps to complete the process:

  1. Back up your iPhone.
  2. When you have a backup, erase your iPhone.
  3. Restore your iPhone from the backup you just made.

Wait, what? Why would I want to unlock the phone if I didn’t have a SIM from another carrier? And isn’t doing a full restore kind of a lot to ask?

As far as I can tell, here’s what’s going on: when you request an unlock from your original carrier, they don’t unlock your phone, they tell Apple’s activation server that your phone is now unlocked. In order to finish the unlock process, your phone has to check in with Apple’s activation server.

There are apparently only two ways to force an iPhone to re-activate with the server: put in a new SIM, or restore the phone. But why would you go the restore route? Because if you’re traveling abroad, when you arrive at your destination and install your newly acquired SIM, it’ll try to contact the activation server. But it can’t reach the activation server because you don’t have data service on your new carrier yet. At this point you’ll be dropped into Activate mode and won’t be able to do anything with your phone until you activate it. If you happen to be somewhere with wifi that doesn’t require any sort of web-based authentication (so, not most airports or hotels) you may be able to activate that way. Otherwise, you’ll have to use iTunes on your computer — assuming your computer can get wifi.

If you won’t be traveling with your computer, or may not have access to a non-cellular internet connection, you’ll want to do that restore at home before your trip. Otherwise, skip the restore and activate through iTunes or wifi.