GSM Coin Payphone with Working Frequency of 850/900/1,800/1,900MHz, Low ... Specifications/Special Features:Specifications: Microcomputer unit control systemAdapts GSM telecommunication modeUsing 5, 20 and 50C, 1 ... ACOutput: 7.5V/1.5AOperating conditions: Working frequency: GSM 850/900/1,800/1,900MHzTemperature: -10 to 40° ... or L/C at Sight GSM Coin Payphone with Working Frequency of 850/900/1,800/1,900MHz ...