GSM Coin Payphone with Working Frequency of 850/900/1,800/1,900MHz, Low Power Indication.. Country of Origin:China (mainland)Brand Name: ... 000mAhExternal adaptor:Input: 220V ACOutput: 7.5V/1.5AOperating conditions: Working frequency: GSM 850/900/1,800/1,900MHzTemperature: -10 to ... Advance or L/C at Sight GSM Coin Payphone with Working Frequency of 850/900/1,800/1,900MHz, Low Power Indication