How do I know if an employee has entered an off-site arrival?

If you suspect that a user has entered an arrival or departure outside of the defined locations, you can check this in the Overview of arrivals and departures report. If one of the defined locations is entered in the Location column of the report, then the user has logged in within a tolerance radius. If the cell is blank, they have either logged in outside the radius or have not enabled location sharing on their mobile phone.