I have a 32GB 3G S, was locked to O2, so I jail broke it on 5.0, updated to baseband 6.15, and used Ultrasn0w to unlock it so I could put in an Orange SIM. This worked fine, but the guy who sold me the phone then told me O2 had notified him it had now ben officially unlocked, so I removed Ultrasn0w and again everything was still fine. Today I went to give the phone to my daughter, so I restored it to stock 5.0.1 firmware, then re-jailbroke, which is fine, except the phone won't activate. Everything else works, it just says "No Service" all the time and iTunes says there is no SIM inserted, and iOS 5's activation screen says "Cannot activate". I found a 5.0.1 custom ipsw online, called "iPhone 3GS-5.0.1_BB6.15.00_Activated", so I booted into pwned DFU mode and restored using that, but the problem persists - "No Service" and can't make or receive calls. I've tired different SIMs, same problem. Anything else I can try?