Today, iPhone dev team has released a new unlocking tool, Ultrasn0w 0.92 to unlock iPhone 3.1.2 firmware. Earlier ultrasn0w 0.9 was working perfectly, but in the latest firmware update it has started giving some weird problems to iPhone users.
After jailbreaking iPhone 3.1.2 firmware with PwnageTool 3.1.4 and unlocking it with ultrasn0w, many users found that carrier name and logo was missing. Now, this bug has been removed from old ultrasn0w tool and ultrasn0w 0.92 comes with proper fix.