How can I avoid roaming charges on my primary SIM card?

Turning off data roaming on your primary SIM card will prevent unexpected high roaming fees when traveling abroad and ensure that all data usage comes from your eSIM. The steps differ between iOS and Android devices:

iOS Devices

1. Go to Settings → Cellular (or Mobile Data in some regions);
2. Select your primary SIM card (not the eSIM);
3. Find Data Roaming and turn off the switch.

Android Devices

1. Go to Settings → Mobile Network / SIM & Network Management;
2. Select your primary SIM card → tap Data Roaming → turn off the switch;
3. This only disables roaming on your primary SIM and won't affect your eSIM.

To prevent your device from automatically switching data cards (and avoid accidental data usage on your primary SIM), we recommend disabling the roaming data switch feature.

iOS Devices

1. Go to Settings → Cellular → Cellular Data
2. Select your eSIM as the Default Data Line
3. Turn off Allow Cellular Data Switching

Android Devices

1. Go to Settings → Network & Internet → SIM Card Manager → Mobile Data
2. Select your eSIM as the Default Data SIM
3. Turn off any Smart Data Switch or similar option (name may vary by brand)