if you have simcard of the locked provider, then you can unlock freely.
Read Here : Flash K800 CID53 with K810 software CID53 (for begginers) - Top Sony Forums but use files only for K800
Here for patch unlock : Patching CID53 (DB2020)DB2010,2012 - Top Sony Forums
and here for generating unlock patch : Remove SIM-lock patch generator - Top Sony Forums