An official OTA Android 4.1.1 (Jellybean) update for the International variant of Samsung Galaxy S3 (i9300) has been leaked courtesy of Samsung-update.com. If you have the know-how in flashing ROMs, then you can already install Jellybean on your device.

We’re not encouraging you to do this as it will void your warranty, but if you still decide to do so, we suggest to watch this video demo first of the buttery OS in action. This may also help you to weigh if the risky flashing is worth it.
With the features shown above, we think it’s better for you to wait for the ROM either OTA or via Kies instead than risking your warranty, which we assume that majority of you are still in it. If you’re still persistent, you can head on over to this site for information on how to install it. The ROM’s download link can also be found there.
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Official OTA Android 4.1.1 update for Galaxy S3 leaked – YugaTech | Philippines, Tech News & Reviews