I'm sorry to break it to you, but that's not gonna happen. It seems nTelos is a CDMA carrie:r, like Sprint, Altell, Verizon, ect. AT&T is a GSM (SIM card) carrier like TMobile, Emmix Wireless, and the rest of the world. You may be able to get them to activate another CDMA carrier's phone (depending on thier policy on that) sorry
P.S. I'll be willing to take the Tilt off your hands if you deside to change
(I'll pay you for it of course)