Installing an eSIM does not always select it for mobile data. Check this before testing the connection.

## iPhone

Open Settings > Cellular or Mobile Data > Cellular Data or Mobile Data, then choose the SimFuse line. Enable that line if it is off. Consider turning off **Allow Cellular Data Switching** to prevent fallback to another line while troubleshooting.

## Android

On Pixel, open Settings > Network & internet > SIMs and choose the SIM for mobile data. On Samsung, look under Settings > Connections > SIM manager > Mobile data. Turn off automatic data switching or backup data on the other SIM where that option is available.

## Check the result

Briefly turn Wi-Fi off and open a small webpage. Match the line's ICCID with SimFuse if labels are unclear. See "[Find your ICCID or EID](https://simfuse.app/help/articles/troubleshooting-find-iccid)".

Keep roaming off on the home line unless you intentionally want to use it and understand the charges. Selecting the travel line for data does not by itself prevent home-carrier charges for calls or texts.

If the correct line is selected but data still fails, see "[Turn on roaming for your SimFuse eSIM](https://simfuse.app/help/articles/troubleshooting-data-roaming)".