... HR999Z02Function:Outdoor Camera for 3 units apartment(intercom system,video door phones)At the last close,install the unit doorway to ... video/audio communication between every sub-phone3) LED in the door station provides a clear picture even at night4) Dingdong or chord ... melody rings are optional5) Intercom, surveillance, remote door unlocking6) Color or B/W is optional, CCD or CMOS ...