This guide covers everything you need to use the Smart SIM, from setting up automatic data switching as a backup connection, to manually switching to Smart SIM when you're travelling abroad.
1. Automatic data switching
Automatic data switching lets your iPhone fall back to your Smart SIM whenever your main SIM loses signal completely, without you having to do anything.
We recommend turning this on so you're always covered in the UK.
Open Settings
Tap Mobile Service
Tap Mobile Data
Select your primary SIM (not the Smart SIM)
Turn on Allow Mobile Data Switching
💡 This only kicks in when your main SIM has no signal at all — your Smart SIM won't interfere with your normal connection day-to-day.
2. Manually switching to Smart SIM
Sometimes you'll want to switch to your Smart SIM yourself, particularly when travelling abroad and you don't want to rack up roaming charges with your main provider. Simply switch to Smart SIM when you arrive in a supported country, and you'll be covered.
Swipe down from the top right of your screen to open Control Centre.
Tap Mobile Data
Select Smart SIM as your data line
Follow the same steps to switch back to your main SIM when you're done.
Alternatively: Settings → Mobile Service → Mobile Data → Select your Smart SIM
3. Manually selecting a network
By default, your Smart SIM will automatically pick the best available network. If you'd prefer to choose one yourself, for example, to test a specific local network, you can do that on your phone.
Open Settings
Tap Mobile Service
Select Smart SIM, then tap Network Selection
Turn off Automatic Selection
The list of available networks will take a few minutes to appear, stay on this page and it will populate shortly.
Tap the network you want to connect to
What happens next? Your iPhone will connect to that network, but may take a few minutes for signal to appear.
⚠️ Switch back to Automatic Selection when you move to a new country or a different part of the UK. While a network is manually selected, your Smart SIM won't be able to move networks automatically, so you may find your connection drops if you move out of that network's coverage area.
You can see which networks are available in each country in our supported countries guide
Need to go back to basics? See the full setup guide