A network system detects lost client devices based on a comparison of geospatial locations transmitted by user and provider client devices during and after a service. The network system assigns a service status indicating that a service from a start location to a destination location is in progress and monitors the locations of the user and provider client devices during the duration of the service and for a specified period of time after the service ends. In response to determining that the user and provider client devices remain in proximity to each other after the service has ended, the network system notifies the user of the lost device.