Being able to carry your usual Spanish SIM card and a foreign data eSIM at the same time is one of the biggest advantages of modern mobile phones. With dual SIM combining eSIM and physical SIM, you keep your number for calls and use local data for browsing, all on the same phone and without changing cards.
What is dual SIM with eSIM and physical SIM
Dual SIM with eSIM allows you to have two lines active at once: your physical Spanish SIM and a data eSIM for your trip. Your usual number still receives calls and SMS while you browse with the local eSIM data, without removing or changing any card. The phone manages both lines independently.
It's different from a "standalone" eSIM: here, the interesting part is the coexistence. You don't give up your home operator (useful for receiving bank codes via SMS, for example) and at the same time you avoid roaming by using data contracted at your destination. Most mid-to-high-end phones from recent years allow this, although it's worth checking before traveling.
Key idea: physical + eSIM don't compete, they share the work. One handles calls for your number; the other, cheap data in the country you're in. You decide which line does what from the settings.
How dual SIM works line by line
When you activate both lines, your phone lets you assign roles to each. Understanding this distribution is what prevents billing and coverage surprises:
- Primary line: usually your physical SIM, with your number, for calls and SMS.
- Data line: the travel eSIM, which handles browsing without roaming.
- Roaming data: disable roaming on your Spanish SIM to avoid extra charges; leave data only on the eSIM.
The important thing is that you can have both lines on but choose for only one to use data. This way you receive calls on your number without paying data roaming, because all browsing goes through the local eSIM. If you want to delve deeper into the technical aspects of the concept, check out our guide on how dual SIM with eSIM works.
How to set up dual SIM on iPhone
On iPhone (from XS and later models) the process is straightforward. Once the eSIM is installed, you go to Settings > Mobile Data and decide which line uses what. It is recommended for travel to set the eSIM as the data line and leave your Spanish SIM for calls.
These are the key steps to set it up correctly from the start:
- Install the eSIM by scanning the QR (Settings > Mobile Data > Add eSIM).
- Under "Mobile Data," choose the travel eSIM as the data line.
- Disable "Allow Mobile Data Switching" so it doesn't switch to your Spanish SIM.
- Leave your Spanish number as the default line for calls and SMS.
With this, your iPhone will make calls with your usual number but will browse with the local eSIM. If you have one of the latest models, you'll find the review of installing eSIM on iPhone 15 and 16 helpful.
How to set it up on Android and Samsung
On Android, the logic is the same, although the menus change depending on the manufacturer. On Samsung Galaxy, for example, you go to Settings > Connections > SIM Card Manager and there you choose which SIM is used for data and which for calls. The key, as with iPhone, is to assign the eSIM to mobile data.
The point where most people get confused is when switching from SIM 1 to SIM 2 for data. Look for it in the SIM card manager: you'll see a "Mobile data SIM" selector where you choose the travel eSIM. Disable data roaming for your Spanish line to avoid overspending and leave the eSIM as the data source. If your Samsung is recent, check how to install the eSIM on Samsung Galaxy for the exact step-by-step for your model.
Advantages and disadvantages of using two SIMs at once
Dual SIM is convenient, but it's also important to know its limits so you don't expect what it can't deliver. Here's an honest balance:
| Advantages | Disadvantages |
|---|---|
| Keep your home number | Only one line uses data at a time |
| Local data without roaming | May consume slightly more battery |
| No physical card change | Requires eSIM-compatible phone |
| Receive bank SMS on your number | Initial setup is a bit more technical |
In practice, the advantages far outweigh the disadvantages for travelers: you remain reachable on your number and pay for cheap data at your destination. The only real drawback is that you have to spend a couple of minutes properly configuring which line does what. Before anything else, confirm that your phone is compatible by checking eSIM compatible phones.
Use cases: when it really benefits you
The eSIM + physical SIM combination shines in very specific daily travel situations. These are the most common among our customers:
- Travel abroad: local data via eSIM and your Spanish number active for banking and contacts.
- Separate work and leisure: one line for professional and another for personal use.
- Business trip: answer with your corporate number while browsing with local country data.
The great advantage is that you don't lose your number or pay roaming fees. If that's exactly what you're concerned about – keeping your number while browsing abroad – we explain it in depth in using eSIM with your same number. And if you travel for work, eSIM for business travel adds useful tricks for not mixing lines.
Frequently asked questions
Can I have two SIM cards with the same number?
Not exactly: each line has its own number. What you can do is keep your Spanish number on the physical SIM and add an eSIM with local data from another number. You receive calls on your usual number and browse with the eSIM without roaming.
Can I use eSIM and physical SIM at the same time?
Yes. Dual SIM phones allow you to have your physical SIM and an eSIM active at the same time. Usually one handles calls and the other handles data. It's the ideal setup for traveling: you keep your number and use cheap local data.
How do I switch from SIM 1 to SIM 2 for data?
On iPhone, go to Settings > Mobile Data, and choose which line uses data. On Samsung and Android, in the SIM Card Manager, there's a "Mobile data SIM" selector. Choose the travel eSIM there and disable roaming for the other line.
Does dual SIM drain more battery?
A little, because the phone maintains two lines connected to the network at the same time. The difference is usually small with normal use. If you notice significant consumption, you can temporarily deactivate the line you're not using or set your Spanish SIM for calls only.
What's better, eSIM or dual SIM?
They don't compete: eSIM is a type of line and dual SIM is the phone's ability to use two lines at once. The ideal for travel is to combine both: your physical SIM with your number plus a local data eSIM functioning as a dual SIM.
Conclusion
Using eSIM and physical SIM at the same time is the perfect formula for traveling: you keep your Spanish number for calls and banking, and you browse with local data without roaming. You just need a compatible phone and a couple of adjustments. Try a data eSIM and activate it alongside your SIM in 1 minute before your next trip.
