< Basic explanation > 1. The local hotspot can be used as a CCTV by connecting a mobile phone and a mobile phone even on a smartphone without a SIM card. 2. It has a built-in streaming server, so if you connect the remaining smartphone to the router at home, turn off the screen after connecting the power, you can access it with another phone from the outside and watch the video like CCTV. 3. I think it can be used as a black box because it can be recorded without a smartphone Internet connecti