Done jailbreak iphone 3gs ios 6.1.2 and unlock tested

After restore iphone 3gs firmware iPhone2,1_6.1.2_10B146_Restore

If not activated just do as below
open
redsn0w_win_0.9.15b3
Select 6.0 ipsw and make install ipad baseband (6.15)
not select install cydia
after reboot phone is activated
Now connect powered on phone to pc and run evasiOn 1.4 and press jailbreak
It will make untethered your jailbreak.
Now you need to unlock do as below..
install ultrasn0w 1.2.8 Deb files Download Click Here
Run Ifunbox or any other file manager program in pc and connect iphone to pc.
place the All DEB files in
var/root/Media/Cydia/AutoInstall
(If Cydia/AutoInstall dont exist, create these folders as posted)
Reboot iPhone normally "twice" and it will be unlocked.

Good luck