Updating old unlocked iphone

[shinyhead]

I have an unlocked/jailbroken 1.0.2 iphone. I wanted to switch back to AT&T and upgrade to 2.2. So is it safe to reuse my AT&T sim card and then upgrade to 2.2 without "bricking" my phone?

Thanks in advance!

 

[showtime]

Yup your phone won't brick. It might be a better idea to restore to 2.2 rather than upgrade to 2.2

 

[shinyhead]

thanks for the quick reply.

so do you mean by restoring to 2.2 by using the restore feature in itunes and use the 2.2 firmware file?