Never tried unlocking my phone but had 3rd party apps. restored the phone then updated to 1.1.1 then iphone said incorrect sim. I decided to down grade and reflash the baseband to 03.xx.xx_x. symptons of a ibrick. the IMEI changed. but was able to work the phone fine with anysim. For some reason even if i did the steps to virgin my phone itunes still wouldnt work with my phone. also my sim message came up again. could it be that at&t blocked me?

Simple version:
1.0.2 baseband 03.14.08_G
1.1.1 BaseBand 04.xx.xx_x
Can't place calls
Downgrade 1.0.2
reflashed Baseband 03.14.08_G
Can place calls and use as it was before

My question is if i downgraded the baseband and virgin the baseband can i ever upgrade to a higher firmware. I heard if i upgrade to 1.1.1 my phone will be really bricked and unable to ever downgrade or work. I also heard that its still unknown what would happen if you were to upgrade the firmware with a reflashed baseband.