Any way to get around this ?

[Richard Desgnr]

I just bought an UNLOCKED Samsung Galaxy S3 mini & it was built for AT&T.
I am using it on TMobile.
When i try to update my 4.2.2 i get the message AT&T Software Update.Current Software is up to date.

 

[anon(777192)]

How do I Upgrade the Firmware for my device using Kies 3?