Reports claim that the iPhone 4S can be unlocked to work on T-Mobile in America without the need for jailbreaking, or running any software.
Apple blog 9to5mac claims that iPhone user Michael Capozzi has found a somewhat strange sequence that confuses the iPhone 4S into working with a T-Mobile SIM card; usually the phone is locked to AT&T.
Commenters on the site are reporting that the instruction do not work, but trying does not seem to risk damaging the iPhone in any way, unlike jailbreaking, which can lead to permanent damage. The hack reportedly works with the iPhone 3GS and iPhone 4, too.
Unlocking an iPhone 4S may invalidate your Apple warranty, and you do so at your own risk.
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
Let us know in the comments below if you have had any success with this somewhat strange unlocking method.