Samsung Galaxy S3 - which one is mine?

Hello everybody

I've got an S3 that I bought online (second hand).
What I want to do is to know what one it is (I guess t999 or i747), but there are some weird things:
- The boot screen shows Samsung Galaxy GT I9300
- The OS is Android JB4.1.1
- The model number in the phone specs is GT-I9300
- CPU-z says:
processor ARMv7 rev4
Device model GT-I9300 (d2vl)
Board: MSM8960
Bootloader: T999UVDMD5
RAM: 1594Mb
Build ID: I9300ZSEMC1
- CPU Identifier says:
CPU type: Qualcomm Snapdragon S4 MSM8960 x2
Smarphone type: Samsung I9300 Galaxy S III
RAM memory module: 2Gb DDR (usable 1594Mb)
GPU type: Adreno (TM) 225
- otherwise, the device seems to allow 4G connexion (not tested, no LTE nearby); it is proposed in the menu
- people from XDA told me I9300 cannot be i-747 or t999

In advance thank you