... Support 2 SIM Cards : GSM(A) and GSM (B),Conveniently choose GSM(A),GSM(B) or PSTN Auto-select ... according setting Five working modes: GSM(A+B),PSTN,PSTN/GSM(A+B),GSM(A),GSM(B) Technical specifications Power supply ... excluding charger current)Application environmentOperating temperature 0~+45CRelative humidity 10%~95%Environment noise ≤60dB(A)Atmospheric pressure 86~106kPa GSM parametersFrequency ...