... 2.two way communication 4.Dual GSM+PSTN alarm Chinese factory SMS security alarm system wireless1.Dual GSM plus PSTN alarm ... , The user can listen in, speak, sound siren, disarm remotely from users phone, when there is alarm 5.groups timed auto ... in, speak, arm, disarm, or turn on/off the siren from a remote phone " Zone is defaulted as below: 1: fire ...