... 1, PSTN & GSM security alarm with LCD display and keyboard 2,99 wireless and 2 wired 3,Voice prompt function 1, PSTN & GSM, Voice prompt ... for each zone, peripheral zone sound alarm, silent alarm around the zone, internal zone audio alarm, silent alarm within the zone, 24-hour ... field, and so on, wired telephone networks can not reach. GSM security alarm system with LCD display and keyboard,, security ...