Oppo A31 4G was officially announced in April 2015, Device released in April 2015Mobile Network Support and BandOppo A31 4G have Dual, (Micro Sim + Nano Sim) Card Slots,Oppo A31 4G support all GSM Based network providers. Oppo A31 4G mobile device support 2G Band Frequency at GSM 850,GSM 900,GSM 1800,GSM 1900 and Hight Speed 3G Network Band at HSDPA 850,HSDPA 1900,HSDPA 2100,Oppo A31 4G also support LTE based 4G Networks Support at Frequency level LTE 1800,LTE 2600,LTE