I just used PwnageTool to upgrade/jailbreak to 3.1 on my 3G. Everything went fine and there were no problems along the way, and I followed the instructions exactly. After syncing everything back to my iPhone, I now get no cell phone signal. My house's wifi seems to be working fine on the phone...it's just the AT&T stuff. This phone has never been unlocked - simply jailbroken. I skipped from 3.0 right to 3.1, and had done my previous jailbreaking with redsn0w. Also, I tried inserting the SIM card from another iPhone into mine, and still received nothing, so I know it's not my SIM. Does anyone think I need to re-jailbreak? I hope not because it took foreverrrr! Any help would be greatly appreciated!!