Post How to - Galaxy S3 Android Upgrade (4.1.1 - 4.3) AT&T Version

Hi,

I have purchased Samsung Galaxy S3 (AT&T) version here is Pakistan, my GSM network is working on but to my curiosity I want to check myself that the phone is fully rooted and it can be used in any country worldwide. (unable to check it GalaxSim Unlocked SW) How can i check it from phone

Secondly when trying to update Android 4.1.1 to 4.3 its checking from About Phone > Software Update > its always going to AT&T Server and checking for update every 24 hours but unable to find it, which is not possible from Pakistan as far I know. Is it possible to update to 4.3 ??

My Cell Phone details are

Model No.: SAMSUNG-SGH-1747
Baseband Version: 1747UCDLK3
Kernel Version: 3.0.31-274808

Waiting for your reply on urgent basis