Push Notification
Depending on the subscription level you have, you may receive alerts on your smartphone via 'push' notifications.
Support
Notifications are not yet supported on Apple devices.
Reliability
Notifications are less reliable than emails. In some cases (such as when the phone is turned off), you may not receive certain notifications.
Additionally, phones may sometimes delay checking notifications in order to save battery.
To improve the reception of notifications, you can disable battery optimizations for Traintrack: Settings > Apps > Traintrack > Battery