I have an 8gb iPhone 2g unlocked and jailbroke on 3.1.2 I have T-mobile's month to month plan for the G1. I recently started having trouble with my data. When I am using T-Mobile's towers, everything is fine, my data is perfect but when it switches to At&t towers, I get an error message. "Could not activate cellular data network." This only appears when I am using At&t towers. I don't understand why this happens. I am connected to edge network and have the "E" notification on the tool bar to indicate it. I did a network reset and it didn't resolve the problem so I did a hard reset, still with no luck. Any ideas?