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Travel eSIM vs roaming
Both get you online abroad. They differ in how you pay, how predictable the cost is, and how much control you have when something goes wrong.
The practical difference
| Travel eSIM | Carrier roaming | |
|---|---|---|
| When you pay | Up front, known amount | Afterwards, on your bill |
| Cost certainty | Fixed — you cannot overspend | Varies by usage and country |
| Setup | Scan a QR code once | None |
| Your phone number | Stays active on your own SIM | Stays active |
| Best for | Trips where roaming is billed per day | Destinations already included in your plan |
The honest summary: if your carrier already includes the country you're visiting, roaming is simpler and you should use it. The moment roaming is charged per day or per megabyte, a prepaid eSIM is both cheaper and more predictable.
What about a local SIM card?
A physical local SIM can be cheaper still, and if you are staying for months it is often the right answer. The trade-offs are practical: finding a shop on arrival, sometimes registering with a passport, swapping out your home SIM and keeping it somewhere safe, and losing your usual number while it's out. Some countries add device-registration rules on top. An eSIM avoids all of that at a modest premium.
If you are travelling from the UK
Since the UK left the EU, free EU roaming is no longer guaranteed by law — each operator sets its own terms. Some plans still include the EU at no extra cost; others apply a daily charge. Outside Europe, a daily fee is the norm. That makes the comparison a piece of arithmetic rather than a matter of opinion:
| What to work out | |
|---|---|
| Roaming | Your provider’s daily charge × the number of days you are away |
| Travel eSIM | The price of the plan that covers your trip, paid once |
Two things make this lopsided more often than people expect. A roaming day is usually charged whether you use 50 MB or 5 GB, and it is charged for every day of the trip, including the ones you spend on a beach with the phone in a bag. A prepaid plan is charged once, for the data itself.
Num plans currently start at $1.14, so on most trips the eSIM is competing with roughly a single day of roaming. That is the number worth holding in your head while you look at your own provider’s rate — and you should look it up rather than take our word for it, because it is the one figure in this comparison we cannot see.
Using both without getting billed twice
The setup that catches people out is leaving the home line free to use data in the background. Keeping both lines active is the right approach — you want calls and texts on your usual number — but the data line has to be set deliberately. Apple’s own guidance is blunt about it: if you keep both lines on, you may still incur roaming fees from the home line.
- Check the phone is unlocked: Settings → General → About → Carrier Lock should say “No SIM Restrictions”.
- Install the travel eSIM before you fly, while you are on wi-fi.
- Turn data roaming off on your home line.
- Set the travel eSIM as the data line: Settings → Mobile Data → Mobile Data, then choose it.
On iOS 26 the phone helps: buy a travel eSIM before leaving and it may ask whether it is for home or travel, prompt you to turn it on when you land, and switch back to your home line when you return. FaceTime and iMessage keep working over the travel data either way.
Settings paths and the roaming warning are from Apple’s guidance on using eSIM while travelling internationally, checked on 2026-08-21.
Common questions
Is a travel eSIM always cheaper than roaming?
Usually, but not always. If your home carrier includes the destination in your plan at no extra cost, use that. An eSIM wins when roaming is billed per day or per megabyte, which is the common case outside your own region.
Can I use both?
Yes, and it is the sensible setup: keep your home SIM active for calls and texts on your usual number, with its data roaming switched off, and run data over the travel eSIM.
Will I still get calls and texts?
Yes, on your normal number, as long as your home line stays enabled. Only data moves to the travel plan.
I am travelling from the UK — is EU roaming still free?
It depends entirely on your plan. EU roaming is no longer guaranteed for UK customers the way it was under EU rules, and each operator now sets its own terms. Some plans still include the EU; others charge a daily fee. Check your provider's own roaming page before you travel rather than assuming either way.
How do I stop my UK SIM roaming while I use the eSIM?
Turn data roaming off on the home line specifically, then set the travel eSIM as your data line. On iPhone that is Settings, then Mobile Data, then Mobile Data, and choose the travel line. Apple notes that if you keep both lines on you may still incur roaming fees from the home line, so the switch matters.
Does my phone need to be unlocked?
Yes, to use an eSIM from another provider. On iPhone, check Settings, then General, then About, and look at Carrier Lock. It should read “No SIM Restrictions”.