I downloaded iOS 7 and install it on my iPhone successfully, but I don't have a UDIS so it can't be activated. How can I get a UDID or downgrade to iOS 6?
I can't activate my iPhone after install iOS 7 Beta?
Please read this first:
If the ROLL Back to iOS 6 doesn't work, you are on your own.
TIP: As stated in the Article, you never should have installed iOS 7, period, because it's BETA!
You need an Apple Dev account to use iOS 7. That's why you can't activate. Better luck next time buddy.