If you didn’t already buy an unlocked iPhone 4S from Apple or take advantage of Sprint and Verizons 90 day unlock request, you can apparently unlock the 4S’s GSM SIM card slot yourself by taking advantage of a strange bug in iOS 5 and how the iPhone 4S handles the Edge network.
Here’s what you’ll need to attempt this:
GSM activated iPhone 4S (AT&T model on contract, for example)
AT&T SIM card
T-Mobile Micro SIM
If you have all of that, completing the unlock is a matter of tripping up iOS 5 by performing a virtual song and dance routine, how someone figured this is out is fairly impressive on its own:
How to Unlock the iPhone 4S
Do this at your own risk:
Insert original carrier AT&T SIM card
Dial 611 for AT&T customer service hotline and drop the call
Turn on Airplane Mode
Take out AT&T SIM card
Insert T-Mobile SIM card
Make sure WiFi is off ( also tap on ‘Forget this Network” to make sure it doesn’t connect automatically later)
Switch off Airplane Mode and iPhone will search for network. This is followed by the Apple splash screen appearing.
Activation Required will be displayed on the screen
EDGE network will activate automatically – notice the ‘E’ on the top left corner of the screen
Wait for about 20-30 seconds and turn off the phone
Turn on iPhone and the same Activation Required screen will be displayed
When you see one signal bar, tap on Use Cellular Connection
Eject SIM card
Activation Required screen will be displayed the second time
Insert SIM card
Multiple users are reporting success with this method, although some had to repeat it many times to get it to finally work.