The alarm will only notify your phone when in Bluetooth range. This range may vary depending on what is between the Scout and your phone, i.e. windows, walls, elevation. Orientation of your phone will also have some influence. It is recommended to enable notifications for the Knog app in the iOS notifications settings.
In a free field environment (line of sight) the bluetooth range should be approximately 60-100 meters. Indoors, or in an environment with structures between your phone and the Scout, the range will reduce to 10-30 meters in most instances.