I'm running out of ideas and hoping somebody can help.
I have an iPhone 3gs running 6.1, new bootrom, 06.15.00 firmware. It was previously jailbroken (5.1.1) and unlocked for use w/ T-Mobile. I never had an AT&T account.
After evasi0n came out and Ultrasn0w was updated to include 6.0 and 6.1, I decided to upgrade. I restored/upgraded to 6.1 via iTunes, then hactivated w/ redsn0w (pointing to ipsw 6.0). After that, I ran evasi0n through Cydia and reinstalled Ultrasn0w 1.2.8. Everything seems to work fine except I can't get phone service. The sim card is fine. It works with another phone.
I've repeated the process above hoping that maybe something just didn't take, but, again, no service.
Has anybody else had success dealing with this problem?