I'm having trouble jailbreaking my 3GS (on ATT). I was starting from 3.0.0. I've used pwnagetool (multiple times) to create a custom 3.1.2 ipsw with activating *not* checked, and have restored to these files, either to old backups or starting completely from scratch. Every time, I have a jailbroken phone running 3.1.2 with the modem firmware still showing as 04.26.08, but I never get a signal, and in settings/general/about it has "Not Available" for network and carrier. What am I doing wrong?! Everything seems great apart from the fact that the phone component is no longer working.