Hello!
I bought my wife an iPhone 3GS that was unlocked/jailbroken on 3.1.3.
After researching for hours, I saved the SHSH blobs (TinyUmbrella) and used PwnageTool 4.1.2 to create a custom IPSW,
updating it to 4.1.
The baseband is 05.12.01.
Now, everything works EXCEPT it won't get service.
It doesn't say "No Service": it shows one bar of service and no carrier name.
I have a factory-unlocked 3GS on Vodafone (we're in NZ),
and I swapped the SIMs across.
Hers has the same symptom with my SIM,
and her SIM works in mine without issue.
I've tried to google for this problem, but every result is for straight-up "No Service" issues,
instead of the weird almost-service-but-haha-just-kidding problem I'm having.
Any ideas?