I found an unlocked iPhone that had a TMobile sim card in it. Because of the passcode I can't get into the phone and because it is jailbroken, I can't seem to restore it to factory settings.
I have a working ATT iPhone and was going to try putting my sim card into this unlocked phone to see if it will allow me to do the restore. I held off though not knowing if I would hurt something else.
My plan was to give this phone to my wife if I can get it up and running.
Re: Can I put a ATT sim card in an unlocked phone?
Make sure your iTunes is upgraded to 9.2. Delete the downloaded software upgrade located (on a iPhone at work so going by memory) c:\document an setting\username\application data\apple\ -- its somewhere in there. Redownload via iTunes and all should be good. It could be trying to install the upgrade for your current iPhone that might not be compatible with the iPhone you found.