Has anyone experienced that the sudden an iPhone has not found any carrier?

I then tried to downgrade to 1.0.2, virgnized, upgraded to 1.1.1, and jailbreaked/software unlocked, but still no carrier sign ... which means I can only use it as an expensive iTouch

Actually i had the same problem with a phone yesterday. When i inserted sim-card it just shown no bars - it didn't say "No service". Tried twice to unlock it, virginize etc, but still no luck. Even upgraded to 1.1.2 and unlocked again. But then suddenly it started working.... Very weird. SIM worked fine in my iphone at all times.