... 2-through RS232 connnect with PC 3-8 wired denfense 4-can expand 127 defense expanding ... 1024 defense bus line intelligent security alarm base; It have 8 wired denfense, can expand 127 defense expanding ... management,editting, handling, support 8 groups of alarm telephone number and 3 groups of central telephone ... up the telephone which the user default to alarm, and tell the user the message in time ...