The do operate on 900Mhz and 1800Mhz bands, which I saw S3 supports. T-Mobile version supports 850, AWS (Band IV), 1,900, 2,100 MHz
UMTS / HSPA+ / DC-HSPA+ for 3G and 850, 900, 1,800, 1,900 MHz
GSM / GPRS / EDGE for 2Gs, 4G depends on market.
Does the Model number of matter in any ways? I...