245.1.2 Call UserPress Call button under standby status, and the VTO will call user. User may monitor VTOfrom VTH. On VTH, press Unlock button to unlock door. When VTH picks up, you can start talk with the VTH. If no one answers the call, then the call will end automatically and device returns tostandby status.5.1.3 Group CallGroup call is mainly used for one VTO. Press Call button on VTO to call multiple VTH atthe same time.VTH consists of master VTH and extension VTH. A system can only have a max of 1master VTH and 5 extension VTHs. Please refer to VTO2000A Series Installation Guide V1.0.0.Set VTOStep 1. Select System Config>Indoor Station Manager, system shows Indoor Stationinterface.Step 2. In Indoor Station Manager interface, click on to delete default VTH.Step 3. Click on Add, input VTH Short No., IP Address (optional) to add a VTH. SeeFigure 5- 2.Note:In Indoor Station interface, you only need to add main VTH, and you do not need to addextension.