cingular. i've been with them for 5 years no major problems, and my bill wasn't bad....when i had one(gotta love a job that gives free cell phone service). the only bad thing about cingular is they seem to be a little behind on the features and cool phones, but they have been catching up lately. and cingular uses GSM/sim card technology vs. version using CMDA which doesn't work outside the U.S.