If you didn’t already buy an unlocked iPhone 4S from Apple, you may be able to unlock the device yourself, for free, without having to tweak your hardware or use a software hack, both of which could void your warranty. Unlocking your iPhone allows you to use it on networks you normally wouldn’t be able to (such as T-Mobile for U.S. residents).
Originally posted by DANIELSCALEB on Pastebin, this hack has been making its way around the web largely due to a Twitter mention by well-known iPhone hacker @Chronic.
The hack does require that you have a SIM card for the network you’d like to use, and the SIM card doesn’t have to be active, which means you could simply buy a MicroSIM from T-Mobile. To perform the unlock, just go through the following steps:
1. Insert original carrier AT&T SIM card
2. Dial 611 for AT&T customer service hotline and drop the call
3. Turn on Airplane Mode
4. Take out AT&T SIM card
5. Insert T-Mobile SIM card
6. Make sure WiFi is off ( also tap on ‘Forget this Network” to make sure it doesn’t connect automatically later)
7. Switch off Airplane Mode and iPhone will search for network. This is followed by the Apple splash screen appearing.
8. Activation Required will be displayed on the screen
9. EDGE network will activate automatically – notice the ‘E’ on the top left corner of the screen
10. Wait for about 20-30 seconds and turn off the phone
11. Turn on iPhone and the same Activation Required screen will be displayed
12. When you see one signal bar, tap on Use Cellular Connection
13. Eject SIM card
14. Activation Required screen will be displayed the second time
15. Insert SIM card
16. Unlocked!
This workaround has not been officially confirmed, although some are already reporting that they’ve had success with this method. Even if you do get your iPhone working on T-Mobile, be aware that you’ll only be able to use slow 2G “edge” data speeds, and you won’t be abe to use features such as Visual Voicemail.
If you decide to try this, do so at your own risk. The below YouTube video shows someone completing the entire procedure – could be helpful if you decide to try this yourself.