Finally, Samsung has started to roll out official Jelly Bean v 4.1.1 for its Galaxy S3 starting from the model GT-I9305 and now this official update by Sammy can be downloaded via Direct Links given in the end.
After a very long delay Samsung seems to be fulfilling it promise, starting off with Galaxy S3. After their latest flagship device has received enough JB updates for everyone to install, then maybe they might concentrate on the first-gen Galaxy Note and its former flagship device Galaxy S2.
Some details regarding this firmware :-
GT-I9305 – Australia (Optus)
As you can see from the above details, this firmware is specifically for Australians on Optus network. So if you want to install this update on your device, make sure you have the i9305 version of Galaxy S3.
Just make sure you have the international GT-I9305 version of Galaxy S3. Download from the link below.
Download Jelly Bean (JB 4.1.1) For Galaxy S3 LTE (GT-I9305) [Direct Link]