Alerts that don't need an app
Emergency alerts reach every phone in range with no app and no internet connection. What that suggests for the apps we build.
If you're in the U.S., you've probably seen an Extreme Cold Warning appear on your phone, even with no weather app installed. The same happens with tornado, heat and flood warnings.
These aren't ordinary push notifications. They don't go through Firebase Cloud Messaging or the Apple Push Notification service. They use Wireless Emergency Alerts, which are built on cell broadcast.
- No app and no internet connection are required.
- The alert goes out from the cell towers to every phone in range.
- People with no Wi-Fi and no mobile data still receive it.
I like this as an example of software doing its job. It protects people, and it asks nothing from them first.
What an app developer can take from it
Anyone who builds mobile apps already knows push notifications. There are a few ways to go further when the message really matters.
- Government alert data. Some governments publish emergency data through open APIs.
- Location-based alerts. Geofencing and location services make a notification relevant to where the person is.
- SMS as a fallback. It reaches people who don't have your app, or who have no data connection.
- Offline first. Keep the emergency information on the device, so it's there when the connection fails.
The message that matters most should depend on the fewest things working.