Use one SIM for calls and an eSIM for data

Keep your number and move only mobile data

Keep the SIM with your usual number enabled for calls and SMS. Set the travel or global eSIM as the mobile data line. This preserves access to calls, messages and two factor codes while the selected eSIM carries internet traffic.

The exact menu names depend on the device and software version. Confirm that the phone is unlocked and supports two active SIMs before you buy a plan.

Before you start

Install the data eSIM while a reliable Wi-Fi connection is available.
Label the existing number line Calls and SMS. Label the new line Mobile data.
Keep the provider installation instructions open. Some providers require data roaming on for their eSIM.
Do not delete an eSIM during troubleshooting unless the provider confirms that it can be installed again.

Set the lines on iPhone

Open Settings, then Cellular or Mobile Data. Add and enable the data eSIM.
Open Default Voice Line. Select the SIM that has your usual number.
Open Cellular Data. Select the global data eSIM.
Turn off Allow Cellular Data Switching if you do not want the calls line to take over data.
Leave data roaming off for the calls line. Set roaming on the data eSIM only when its provider instructs you to do so.

Set the lines on Android

Google documents these controls for Pixel phones. Other Android manufacturers can use different names.

Open Settings, then Network and internet, then SIMs. Add and enable the data eSIM.
Set the preferred SIM for calls and SMS to the line with your usual number.
Set the preferred SIM for mobile data to the global data eSIM.
Turn off automatic mobile data switching if the phone offers that control.
Leave roaming off for the calls line. Follow the eSIM provider's roaming instructions for the data line.

Protect number and messaging continuity

Keep the calls and SMS line enabled if you need incoming messages or two factor codes.
Installing a data eSIM does not require changing the number registered in WhatsApp or another messaging app.
Do not accept a number-change prompt in a messaging app unless you intend to move that account.
iMessage line choices depend on the enabled lines and Apple ID settings. Check Send and Receive after the eSIM is installed.
Carrier charges for calls, SMS and roaming on the number line remain subject to that carrier's terms.

Test both lines

Turn off Wi-Fi and load a webpage. The phone should show the global eSIM as the mobile data line.
Make a short call and send an SMS. The phone should use the usual number line.
Check the calls line settings again. Mobile data and data roaming should remain off on that line.
Check the provider app or account page for plan activation and usage state.

Recover from common setup errors

The eSIM has no data: Confirm that the eSIM is enabled and selected for mobile data. Check its roaming and access point settings against the provider instructions.
Calls use the wrong line: Set the default calls and SMS line again. Keep the line with the usual number enabled.
The calls line uses mobile data: Turn off mobile data switching. Turn off data roaming for that line and reselect the eSIM as the data line.
A messaging app asks to change number: Cancel the prompt unless the account number should change. Confirm the app's registered number in its account settings.

Official device sources

Device guidance checked 2026-08-11.

Apple Dual SIM with eSIM: Official source
Google Pixel two-SIM controls: Official source