I find out that k800 is only db2020, so it doesn't matter.
But you should check what is your CID. If you want to unlock your phone it must be CID52. If it's lower you should upgrade it using SEUS.
Just do an identify using setool2lite. Also you should save the GDFS. But first read the sticky tutorials for setool2lite.
Se Tool 2 Lite - Top Sony Forums