Yes it works directly with the STB when the rf battery is removed. I did remove or disable the HTD extender for testing. When testing I was able to get the ATT box to power on at random times, however all other previously working functions pretty much stopped even in direct line of sight. So Picture this- tv on the wall, closet door within 1 foot of the edge of the TV. Reciver and STB now in closet. If I have line of site I can control STB but the door need to be open. I do not have the USB adapter I see in your att remote link. I searched on ATT and see there may be 3 others that look same, but are not claiming RF. I assume it must be RF since all other commands (tv, AUX) will light up the eye when commanded, yet the ATT (channel up, down, guide etc) do not illuminate the eye.
CAn I call someone at ATT? Hell no it takes an hour to get someone who knows nothing. NOt even going there.