GSM phone on cingular?? HELP PLEASE!!?

you will be able to use this phone on at&t but you probobly will not get any signal depending on where you live. at&t operates on the 850 and 1900 bands in the US. that phne is a tri-band phone, but for 900/1800/1900, its lacking 850 which means you will not get any signal in some places