iPhone dual SIM setup for a UK number and travel data
If you have bought a giffgaff physical SIM from LarkSIM and want to keep a UK number on your iPhone for text messages, you may also want a destination-specific travel data plan for maps, browsing and messaging apps when you travel abroad. This guide addresses that setup.
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The aim is to keep both lines on the phone, with giffgaff receiving texts sent to your UK number and the travel plan providing internet access. You need to check whether your iPhone supports the combination, choose the travel plan as the data line, and keep giffgaff available for SMS without unintentionally using its roaming data. The steps below assume you are keeping the giffgaff physical SIM and adding a separate travel eSIM.
Apple and giffgaff document dual SIM support, but the available combinations depend on the handset. Carrier support also matters. In particular, giffgaff does not currently support Wi-Fi Calling outside the UK. A working travel data connection should not be treated as a universal workaround for a giffgaff line with no roaming service.
Check the two-line combination
Confirm the exact iPhone model, sales region and carrier-lock status before purchasing. Storing several eSIM profiles does not mean every profile can be active together.
Keeping a giffgaff physical SIM and adding another provider's travel eSIM creates a two-line setup. Replacing the giffgaff physical SIM with an eSIM on the same account replaces the original SIM; it does not create a second copy of that number.
Set things up where you have reliable internet. Check when the travel package starts counting its validity before installing or testing it. Installation and the start of paid service can follow different rules.
Assign data and voice deliberately
In Settings, open Cellular or Mobile Data and give the plans descriptive labels, such as UK Number and Travel Data.
1. Select Travel Data as the cellular data line.
2. Choose a voice-capable line for default calls. A data-only travel plan cannot provide ordinary cellular calls.
3. If you want to prevent automatic data fallback, leave cellular data switching off initially. Review the other line's charges before enabling it.
4. Check data roaming separately for each line. Follow the travel provider's instructions and disable roaming data on giffgaff if you do not intend to use its overseas data service.
Disabling roaming data is different from disabling the entire line. Leave the UK line enabled if you want ordinary SMS, and check that it registers on an available roaming network.
Verify each kind of communication
A working web page confirms data access. It does not prove that ordinary SMS or phone-number-based iMessage works.
Under Settings, Apps, Messages, check Send & Receive and the identity selected for conversations. A UK number needs its own completed iMessage setup. An email-based iMessage exchange does not confirm SMS service on the SIM.
If giffgaff has no service abroad, investigate its account and roaming connection. Do not assume another carrier's Backup Calling instructions apply to it.
Finish with a practical test
Turn Wi-Fi off and load a normal web page using the travel line. Ask a trusted contact to send an ordinary SMS to the UK number, then exchange an iMessage and check the sender identity. Review charges before making a test call.
If data and ordinary SMS both work, the basic division is complete. An iMessage-only failure belongs in the iMessage activation flow; an SMS failure belongs with the number's cellular service. Do not delete an eSIM to troubleshoot messages unless you have confirmed how it can be reinstalled.