I have a previously jailbroken/unlocked iPhone 3Gs that was running 3.1.2 firmware and I forget what baseband. I restored to the official 4.0 firmware via iTunes and then ran Redsn0w 0.9.5b5-4 to jailbreak.
Redsn0w ran it's process smoothly, but when it finished and rebooted went straight to 'Emergency Calls' screen. When connected to iTunes, it tells me my sim is not supported.
I've tried running Redsn0w over again, as well as restoring via iTunes again first. I keep getting through the process with no problems but ending up in Emergency Calls mode, with no hacktivation.
Any ideas would be appreciated.
(btw, iTunes also tells me my iPhone firmware is up-to-date, so I guess I'm now running 4.0 with whatever baseband is the latest one)