
Samsung GALAXY S III
The latest firmware for Samsung GALAXY S III (SGH-I747) is I747UCDLK3 with Jelly(Android Bean), released on November 14, 2012 for 1 region (CSC). Every official firmware build for SGH-I747, newest first: one row per build with all regions (CSC) that received it.
You can find the firmware on the model: SGH-I747 page.
Yes, all firmware files for SGH-I747 are 100% official, original, and obtained directly from Samsung servers.
To flash SGH-I747, you need to download the appropriate firmware, put your device into Download Mode, and use the Odin tool to load the BL, AP, CP, and CSC files.
Downgrading is only possible if the bootloader version (binary bit) of the old firmware matches the current one. Always check the binary version before flashing SGH-I747.