An example implementation involves a media playback system that includes one or more playback devices that are controllable by the mobile device while the mobile device is joined to the media playback system. The mobile device may join the media playback system over one or more communication paths via a cellular network from the mobile device to the media playback system. The example implementation may involve detecting that the mobile device is outside of a threshold proximity to the media playback system while the mobile device is joined to the media playback system. Based on detecting that the mobile device is outside of the threshold proximity to the media playback system, the mobile device may disconnect from the media playback system.