Sprint Galaxy S3 has a Samsung Jelly Bean Firmware too. Port of T-Mobile One, Actually

Just a week ago, T-Mobile Galaxy S3 owners were surprised with the leak of an official Android 4.1 Jelly Bean firmware, which gave them a glimpse of how the official Android 4.1 will be when it officially releases. Owners of other US variants of the device probably looked on in jealousy, but those on the Sprint Galaxy S3 can now throw their jealous feelings out the window, as the Samsung Jelly Bean firmware for the T-Mobile S3 has been ported over to the Sprint Galaxy S3, by XDA Elite Recognized Developer myn.

That’s right, if you want to try out the official Jelly Bean firmware from Samsung on your Sprint Galaxy S3, you can do so thanks to the port of the Jelly Bean firmware for the T-Mobile Galaxy S3, which can be flashed from ClockworkMod recovery. The ROM is pre-rooted and retains everything from the original firmware, including all the T-Mobile specific apps. Keep in mind that this ROM is based on a leaked unfinished firmware and hence may have a few bugs present so it should not be considered a ROM for daily use.

Let’s take a look at how the Samsung Jelly Bean firmware can be installed on the Sprint Galaxy S3.

Compatibility

This guide below is compatible only and only with the Sprint Galaxy S3, model number SPH-L710. It’s not compatible with any other Galaxy S3, it only works for Sprint variant. Check your device’s model in Settings» About phone.

Warning!

The methods and procedures discussed here are considered risky and you should not attempt anything if you don’t know completely what it is. If any damage occurs to your device, we won’t be held liable.

How to Install Jelly Bean Firmware ROM on Sprint Galaxy S3

This procedure will wipe all your apps, data and settings (but it will NOT touch your SD cards, so don’t worry about those). Backup your Apps and important data — bookmarks, contacts, SMS, APNs (internet settings), etc. This Android backup guide would help you.
NOTE: Don’t forget to at least note down your network’s APN settings, which are required to make mobile data work. Go into Settings » More » Mobile Networks, click on the APN that is in use, then note down the setting for each field. While APN settings should be automatically restored from network, you can enter them manually if needed to make mobile data work. You can also find your APN details → here.
Install ClockworkMod recovery on your phone by following the guide → here. Skip if you already have ClockworkMod recovery installed.
Download the latest version of the ROM from the source page.
Copy the downloaded zip file from step 3 to the internal SD card. Do not extract them.
Now, boot into ClockworkMod recovery. To do that, turn off your phone. Then, hold down Volume Up, Home and then the Power buttons together until the screen turns on, then let them go. The phone will boot into ClockworkMod recovery in a few seconds.
In recovery, use the volume buttons to scroll up/down and the home button to select an option.
Perform a Nandroid Backup of your existing ROM, so that you can always restore it from recovery if something does not work out with this ROM. To perform a backup, select Backup and Restore –> On the next screen, select Backup again. Go back to main recovery menu after backup is complete.
Select wipe data/factory reset, then select Yes on next screen to confirm. Wait a while till the data wipe is complete.
Select install zip from sdcard, then select choose zip from sdcard. Scroll to the ROM file on the SD card and select it. Confirm installation by selecting Yes – Install _____.zip on the next screen. The ROM will start installing.
After the ROM finishes installing, select go back then select reboot system now to reboot the phone into the ROM.
[SMS Fix. Only needed if SMS doesn’t work for you] If you find that after the ROM boots up you cannot send SMS or the Messaging app doesn’t open, then do the following:
1. Download the SMS fix file.
  Download Link
2. Copy the downloaded file to internal SD card. Then, turn off the phone and boot into ClockworkMod recovery.
3. In recovery, simply repeat step 8 but select the SMS fix file (instead of the ROM file) to install the SMS fix. After installation is complete, reboot the phone.
NOTE: If you want to go back to your previous ROM, boot into recovery, select backup and restore then restore your previous ROM by selecting it from the list.