Robin uses a variety of methods to know when someone is in a room.
One way is through Robin's meeting room display app, Rooms. Rooms is a companion app for Robin that runs on iPads and Android tablets. Mount displays outside of conference rooms to keep schedules and events updated in real time.
Watch the tutorial or follow the steps below
Scan the QR code to add the room to new or existing meetings 
Scan the QR code with your phone to open the Robin mobile app and complete your booking for a new or an existing event. If the event is within your office's check-in window, then you'll automatically be checked in.
Start impromptu meetings from the display
Start an impromptu meeting by selecting a meeting duration. These are ad hoc meetings that are considered "anonymous" bookings. Admins can disable this functionality under the "Display scheduling" settings.
Rooms will let you know how long the space is available until the next meeting (e.g., Available for 85 minutes).
Check in to scheduled meetings & mark rooms as in use
Tap check-in on the room display or scan the QR code to check in from the mobile app.
View the daily agenda for the space
View the event organizer and event attendees
View info about the space, and system info for the display
Alert facilities teams to any problems with the room 
See the availability of nearby spaces
Rooms background colors, decoded
Green = Available
Green means go. This room is available for you to use now. Rooms will let you know how long the space is available for until the next meeting (e.g. Available for 2 hours).
Yellow = Booked
Yellow shows the room is booked, but no one has checked in. To check-in, tap Start this meeting.
If your office doesn't have the meeting check-in button enabled the room display will go straight to red and assume the scheduled meeting is in progress.
Red = In Use
Red shows when the room is in use. Someone has started a meeting.
The above color decoding is based on Room's default colors. If your office has the meeting check-in button disabled, then the room display will show red ("in-use") and assume the scheduled meeting is in progress. Learn more on custom color settings here.
Admins can remotely manage display settings by navigating to the management page for the space it's paired with. Navigate to Manage > Offices in the web dashboard, then click the location and the name of the space's display you'd like to update.