Sony Mobile has recently started to sell the Xperia C4 (E5306) in the United States, unlocked through Best Buy. The variant being sold is 4G LTE compatible and will work with AT&T and T-Mobile US. Best Buy is selling the handset for $274.99 with free shipping and it is available in black and white colours.
Xperia C4 (E5306) bands
UMTS HSPA+ 900 (Band VIII), 850 (Band V), 1700 (Band IV), 1900 (Band II), 2100 (Band I) MHz
GSM GPRS/EDGE 850, 900, 1800, 1900 MHz
LTE Bands 2, 4, 5, 7, 12, 13, 17
