The DoorCom IP from Siedle USA links the supplier's door station security intercom product to a TCP/IP network/Intranet. The system enables a PC to take on the functions of the indoor call station, including video transmission, camera control and switching and signaling functions. Up to 31 different PC users can be selectively addressed. Other features include full duplex audio connection by headset or standard public network telephone; optional speech connection; and audio link between indoor devices and PC call stations within one line.