... function GSM telephone alarm systemDescription:1 16 wireless zones, can totally add 16 wireless detectors, automatically dail and send SMS to ... 1 GSM network: 900/1800/1900MHZ(850MHZ optional)2 GSM antenna: mobile antenna: gain 4dbi, cable length: 3-5m, SMA connector portable ... antenna: gain 2dbi, height 10cm,SMA connector3 receiving frequency: 433/ ...