This is my 1st thread to guide you to correct resource rather as many of us have struggled to root the AtT ICS version ROMs.
I was on leaked iCS v18f installed immediately when available, struggled hard to root it.. Tsparky, Doomlord, SuperOneClick, manual root,. No go for more than a couple of months.. Found the Bin4ry root method:
Worked in 1st attempt.
Thought it should work on V20c as well,, upgraded to v20c.. rooted in 1st attempt again (no surprise there)
UI is smooth as silk and response is awesome..
Right now Rooted, no-frills CPU, ADW Launcher Ex and Network Selection Tweak by -ReaL-. (as the *#*#4636#*#* code to choose network selection is removed on V20c) THANKS A LOT..
My Phone is a like a ripe cherry for the 1st time and I am jus loving it...
Thanks to all the mods and developers..
NOTE: Confirmed working on both ICS versions V18f and v20C, single attempts, though doesnt work on Gingerbread as explained in the linked post.