There is no SIM card installed after IOS update on 3GS

Hey!

I just upgraded my iPhone 3GS to iOS 5. All went well, then at the end, it asks me a few set ups (like language, Location, and WiFi settings).

After that, it attempts to activate, and fails, giving me the following error in iTunes: "There is no SIM card installed in the iPhone you are attempting to activate."

Problem is, there IS a SIM card in the phone, I tried taking it out, and putting it back in, tried with another SIM, tried the SIM in another phone, worked fine, just not the iPhone!

I would appreciate any help!

Also, the phone was Jailbroken before, and the SIM worked fine. Just not now, when it tries to activate.

IS IT POSSIBLE TO GO BACK TO THE BEST PREVIOUS UPDATE OF IOS4. THAT"S ALL I EXPECT NOW!😢