You can upgrade ur OS. But you have to delete the vendor file first.Crackberry.com is the best site for questions like these. Link Here:
http://forums.crackberry.com/f5/newest-8100-os-v4-5-0-124-multilanguage-138241/
Back up ur Berry before you attempt this!
...software device? I moved to the Dominican Republic and I'm using the carrier: Claro Dominican. But I want to upgrade my device software. But I don't know if the device can lock itself again, and I will to unlock it again. Is it safe? and the other question is Can I download the AT&T device software, because I've been trying to download the T-Mobile one and they're asking me for the cell phone number, which I don't have. What Can I do?