Cingular eliminating TDMA!?!

Cingular Wireless seems to be slowly eliminating it's existing TDMA towers, and running only the GSM towers in thier place. I currently have a TDMA Nokia phone that I purchased from AT&T Wireless. I was always able to recieve a TDMA signal, even after the aquisition by Cingular. My girlfriend has a GSM phone from the former AT&T. I often use my phone near an Arlington tower. Within the last two