For AT&T Galaxy S2 SGH-i777, you can “hellraise” a GT-i9100 ROM to work on your AT&T Galaxy S2. Since both phones are nearly identical except modem and menu buttons, it makes it easy to interchange ROMs. You can look for hellraiser tools on XDA if you are interested in doing this yourself.
Resurrection ICS ROM is also now available for your AT&T Galaxy S2 via Hellraiser. This ICS ROM is fully functional just as the original i9100 version, the only bug is that the screen randomly turns on by itself in sleep mode.
Well, hellraising isn’t perfect but it can help you enjoy i9100 ROMs on your SGH-i777.
Download Resurrection ICS ROM
You can see original review of Resurrection ICS v.1.8.1 here.
Credits – XDA
Don’t know how to install a ROM?
For all AT&T Galaxy S2 SGH-i777, please see AT&T Galaxy S2 FAQ here for all rooting, backup, install guides.