Default Is unlocking boot loader possible

I am curious if it is possible to unlock the bootloader on my LT28AT? I went to Sony's website and they claim my phone is not supported via their unlocking procedure I did get a key code but am not sure if it will brick my phone so I haven't tried yet

Sent from my LT28at using XDA Free mobile app
Now my LT28at thinks its an LT28h

So many frustrations so little time