Your phone can warn you at a threshold you choose, which is a useful backstop alongside the app's own low-data notification.

## Android

1. Open Settings, then Network and internet, then SIMs.
2. Choose the SimFuse line.
3. Open the data warning and limit settings.
4. Set a warning, and a limit if you want the line switched off automatically.

## iPhone and iPad

iOS does not have a per-line data limit. What it does have is a usage counter per line in Cellular settings, which you can reset when your plan starts so the figure means something.

## A more useful habit

Check the app rather than the phone. It shows what the network has counted, which is what your plan is measured against. See "[Check how much data you have left](https://simfuse.app/help/articles/plans-check-data-left)".

## Turning off the biggest consumers

- Turn off automatic app updates over cellular.
- Turn off background app refresh for apps you do not need live.
- Download maps and playlists before you travel.
- Lower video quality in streaming apps, which is where most surprise usage comes from.