... requirments and functions of seeing ,listening ,recording and setting.According to requirments of different hosts, select NC,NO or voltage input ... E1,E2,E3,E4,indictor all will on8, connect to telephone line9,Connect to DC12V, Orange color cable (+) Possitive, Brown(Balck) color ... so on, so have this feature , it can automatically calls to extension phoneconnect to (#) to telephone Auto dialer