... function 3.3SMS,3calls on alarming 4.PIR sensor+detect GSM wireless home security alarm G121.8 wireless zones 2.Intercom ... alarming 4.PIR sensor+detector Description and Main functions1.Wavecome GSM module. 2.8 wireless zones( 1 wireless SOS zone, 1 ... .15. Can send alarm signals to monitoring center through GSM network, such as the police station.GSM frequency:G12E GSM900/1800MHZG12EA GSM850/1900MHZ