If you have got an unlocked and jailbroken iPhone 3G or iPhone 3GS running firmware 3.1.2, then you must have noticed by now that the carrier name or logo on the top left side of the status bar is missing as shown in the screenshot below:
According to Dev-Team, this is caused due to a known bug in ultrasn0w and PwnageTool and it is purely cosmetic, which means your phone works fine even without the carrier logo in place. Fortunately, there is a workaround to this which can bring back carrier logo of your choice:
Step 1: Goto “Cydia” on your unlocked and jailbroken iPhone 3.1.2, search for “MakeitMine” app and install this app.
Step 2: Start “MIM” app on your iPhone and type the name of your carrier:
Step 3: Touch on “Carrier” button on the top left to save your changes.
Voila! You should now have your carrier logo back in place on a jailbroken and unlock iPhone 3G/3GS running on firmware 3.1.2.
UPDATE 1: ultrasn0w 0.92 has been released which fixes the missing carrier logo/name on unlocked iPhone 3.1.2 firmware. For more info, follow the guide posted here.
If you liked this, then you may also like checking out How to Enable Tethering on iPhone 3.1.2 Firmware.