You bought a travel eSIM, but your phone is still using your main SIM for data.
This is one of the most common dual SIM travel mistakes. Many phones can keep your home SIM active for calls and texts while using the eSIM for data — but only if the settings are configured correctly.
If not, your device may continue using your primary SIM, which can lead to roaming charges or the travel eSIM appearing “not to work.”
This guide explains exactly why your eSIM is using your main SIM instead and how to fix it quickly.
Quick answer: Set the travel eSIM as your Mobile Data line, disable automatic data switching, and keep your main SIM only for calls/texts if needed.
Why this happens
Modern phones often support two active lines:
- Main/home SIM
- Travel eSIM
But your phone uses separate settings for:
- mobile data
- calls
- texts
- default voice line
If mobile data still points to your home SIM, the eSIM may stay idle.
1. Mobile Data line is still set to your main SIM
This is the #1 cause.
Fix:
- Open SIM / Cellular settings
- Find Mobile Data
- Select your travel eSIM
2. Automatic Data Switching is enabled
Some phones automatically switch data lines when signal changes.
This can unexpectedly return data to your main SIM.
Fix:
- Disable Allow Cellular Data Switching (iPhone)
- Disable similar smart switching settings on Android
3. Main SIM roaming still active
If your home SIM roaming remains ON, the phone may continue using it.
Fix:
- Turn OFF roaming on the main SIM
- Keep roaming ON for the travel eSIM if required
Helpful guide: Do You Need Roaming for eSIM?
4. eSIM line is installed but disabled
The eSIM may exist but not be turned ON.
Fix:
- Go to SIM settings
- Enable the travel eSIM line
5. Calls and data settings are mixed up
Some travelers confuse voice line with data line.
You can usually keep:
- Main SIM = calls/texts
- Travel eSIM = mobile data
This is often the best travel setup.
Best dual SIM travel setup
Main SIM
- ON for calls/texts if needed
- Roaming OFF
Travel eSIM
- ON
- Mobile Data selected
- Roaming ON if provider requires
iPhone fix path
- Settings
- Cellular
- Cellular Data → Travel eSIM
- Allow Cellular Data Switching → OFF
- Main SIM Roaming → OFF
Android fix path
- Settings
- Network & Internet
- SIMs
- Preferred Data SIM → eSIM
- Main SIM roaming OFF
Fast 60-second fix checklist
- Select eSIM for data
- Disable auto data switching
- Main SIM roaming OFF
- Travel eSIM roaming ON
- Restart phone
How to know it is fixed
- Carrier name changes to travel network
- Data icon tied to eSIM line
- No roaming alerts from home carrier
- Travel eSIM data usage increases
Common traveler mistakes
Turning on eSIM but never selecting it for data
Very common.
Leaving home roaming ON
Can trigger charges.
Assuming calls setting controls data
They are different settings.
Using auto switching abroad
Manual setup is safer.
When to contact support
Contact support if:
- eSIM selected but no data works
- main SIM keeps taking data anyway
- device menus behave strangely
- dual SIM profile issue suspected
Helpful page: Contact Support
Final thoughts
If your eSIM is using your main SIM instead, the issue is almost always phone settings — not the eSIM itself.
Set the travel eSIM as your mobile data line, disable switching features, and keep your home SIM for calls only if needed.
Need easy travel data? Browse travel eSIM plans with fast setup and support.
FAQ
Can I use main SIM for calls and eSIM for data?
Yes. That is often the best travel setup.
Why am I getting roaming charges with an eSIM installed?
Your main SIM may still be the active data line.
Should I turn roaming off on my home SIM?
Usually yes, to avoid accidental charges.
Should I disable automatic data switching?
Yes, especially while traveling.
Does installing an eSIM automatically switch data?
No. Many phones require manual selection.