At the moment no jailbreak tool works for iPhone 4S but a developer named Michael Capozzi has found a way out to unlock AT&T iPhone 4S without the help of any third party adapters like geveySIM.
Remember, its not a permanent unlock so you have to perform this unlock process whenever your iDevice will get restart.
Warning: We are not responsible for any loss so proceed at your own risk.
Unlock iPhone 4S on AT&T
Requirement
- T-Mobile data plan
Step-1
Insert AT&T SIM card
Step-2
Dial 611 for AT&T customer service hotline and drop the call
Step-3
From “Settings” menu on your iPhone, Turn ON “Airplane” mode
Step-4
Remove AT&T SIM card and insert T-Mobile SIM card
Step-5
Turn OFF WiFi and use “Forget this Network” option to make sure your device should not connect automatically to any network
Step-6
Turn OFF Airplane mode and your iPhone will start search for network and it will display Apple splash screen
Step-7
It asks for Activation and your iPhone will automatically get connected to EDGE network and you will find ‘E’ on top left corner of the screen
Step-8
Wait for 20-30 seconds and then Turn OFF your iPhone
Step-9
Turn ON your iPhone and again it displays Activation Required screen
Step-10
When there will be only a single signal bar, tap on “Use Cellular Connection”
Step-11
Eject SIM card
Step-12
Activation Required screen will display again
Step-13
Insert SIM card back
Enjoy, your AT&T GSM iPhone 4S is unlocked which can work over T-Mobile as well.