GSM Coin Payphone with Working Frequency of 850/900/1,800/1,900MHz, Low Power Indication.. Country of Origin: ... : 220V ACOutput: 7.5V/1.5AOperating conditions: Working frequency: GSM 850/900/1,800/1,900MHzTemperature: -10 to 40°CRelative humidity: 45 ... /C at Sight GSM Coin Payphone with Working Frequency of 850/900/1,800/1,900MHz, Low Power Indication