I have found Cingular(GSM) service to be the best I've used(and i've used plenty of providers). These Proviers include Virgin Mobile (Sprint)(CDMA), Verizon(CDMA), Cingular(GSM), and CellularONE(CDMA, local company). I have also used a ton of different phone including: Vox 8500(Virgin, CDMA), Vox 8610(Virgin, CDMA), Kyocera K9(Virgin, CDMA), LG VX3200(Verizon, CDMA), Motorola C343(CellularONE, CDMA), Kyocera Phantom(CellularONE, CDMA), Kyocera Energi(CullularONE, CDMA), Motorola V551(Cingular, GSM), Nokia 6230(Cingular, GSM), Sony-Ericsson T237(Cingular, GSM), Sony-Ericson S710a(Cingular, GSM), Sony-Ericsson T290a(Cingular, GSM). Cingular has had the best call quality and reception, followed (closely) by CellularONE, then Virgin. My service with Verizon was abysmal, call quality sucked and i had no service in most places. Anyway that's my 2 cents, hope it helps.