Samsung Galaxy S3 devices are still running Android 4.1.2 Jelly Bean and the Android 4.2.2 Jelly Bean update looks really far away for these smartphones. However, the Galaxy S3 smartphones on AT&T can now enjoy the features of Android 4.2.2 Jelly Bean via custom ROM till the official Android 4.2.2 Jelly Bean update gets rolled out for the devices.

The update comes to the Galaxy S3 devices on AT&T SGH-I747 via CM10.1 M3 custom ROM.

The custom ROM is a nightly build and after installing this, your device may get FC errors and other bugs and complications. To fix it, you will have to reinstall stock firmware or any other stable custom ROM.

As this is not an official Jelly Bean update, you will require custom recovery like ClockworkMod to flash the ROM zip and Google Apps zip files on your Samsung Galaxy S3 smartphone.

Before you go ahead with the installation process, keep one thing in mind: there are always chances of the device experiencing bricking issues. That only happens if the rooting is not done properly and the instructions are not followed step-by-step.

Follow these steps to prepare your device for the big task:

1:  The process is meant only for AT&T Samsung Galaxy S3 SGH-I747. Therefore, users are advised to check their devices' model number in: Settings > About phone.

2: Make sure the device has at least 80 percent of battery backup.

3:  Download and install USB drivers for your Galaxy S3 and enable the USB debugging mode.

4: Back-up all your important data.

5: Download and install ClockworkMod recovery.

6: Download CM10.1 M3 Android 4.2.2 ROM.

7: Download Google Apps

8: All the custom ROMs, firmware, official firmware updates, tools and anything mentioned in this tutorial belong to their respective developers. Mobile&Apps will not be held responsible for anything that goes wrong.

Now you are all set to start the smooth task; just follow the instructions given below step-by-step:

1: Connect your Galaxy S3 to your computer via micro USB cable.

2: Copy and paste the downloaded CM10.1 M3 Android 4.2.2 ROM to your phone.

3: Switch the device off and detach the USB cable.

4: Press and hold the Power + Volume Up + Home Button to enter ClockWorkMode Recovery.

5: In Recovery menu, you are always recommended to perform a full Wipe Data/Factory Reset to avoid crashing and ROM compatibility issues. It is an optional step if you upgrade from your previous ROM version. For CWM recovery, use Volume key to navigate in Recovery Mode. For TWRP, use touchscreen to navigate in Recovery Mode.

6: Do Wipe Cache Partition - Select from the menu and select Yes to confirm.

7: Go to advanced and do Wipe Dalvik Cache - Select from the menu and select Yes to confirm.

8: From the main menu in Recovery, select the install zip from SDcard, then select choose zip from internal SDcard, browse to folder location and select the CM10.1 M3 Android 4.2.2 ROM and click Yes to install.

9: Back to main menu in Recovery, select the install zip from SDcard, then select choose zip from internal SDcard, browse to folder location and select the Google Apps file and click Yes to install.

10: After the installation completes, go back to recovery's main menu.

1. Select reboot system now to reboot the phone.

2. For first boot up, it normally takes a longer time. Please wait patiently.

 [Source: Team Android]