How travel eSIMs work, whether your phone supports them, how they compare with UK network roaming add-ons and local SIMs, how to set one up before you fly, and the mistakes that lead to surprise bills.
Since the UK left the EU, most major UK mobile networks have brought back charges for using your phone in Europe on many plans, often as a daily fee. Further afield, roaming can be expensive. A travel eSIM is one way to get mobile data abroad at a known price. Here's how they work and when they're the best option.
What is an eSIM?
An eSIM is a digital SIM built into your phone. Instead of inserting a plastic card, you download a profile, usually by scanning a QR code or through an app. Most phones can hold several eSIM profiles and use two lines at once, so you can keep your UK number active for calls and texts while using a travel eSIM for data.
Check your phone first
- Compatibility: most recent flagship and many mid-range phones support eSIM, but some cheaper models don't. Check your phone's settings or the manufacturer's website.
- Unlocked: your phone must be unlocked to use another provider's eSIM. Phones bought from UK networks since December 2021 must be sold unlocked, but older handsets may still be locked. Ask your network.
Your options for data abroad
| Option | Good for | Watch out for |
|---|---|---|
| Your UK network's roaming add-on | Short trips, simplicity, keeping everything on one line | Daily charges add up on longer trips; fair use limits |
| Travel eSIM | Data at a fixed price, multi-country trips | Data-only plans usually have no local number; validity periods |
| Local physical SIM | Long stays, heavy data use | Registration rules and ID requirements in some countries; swapping SIMs |
| Wi-Fi only | Saving money | Public Wi-Fi security; no data when out and about |
Some UK plans still include roaming in some destinations, so check your own plan before buying anything.
Setting up a travel eSIM
- Buy a plan for your destination and check the data allowance, validity period and which local networks it uses.
- Install it at home over Wi-Fi a day or two before you travel. Many plans only start their validity when they first connect abroad, but check.
- Label the lines, for example "UK" and "Travel".
- On arrival, set the travel eSIM as your mobile data line and turn on data roaming for that line if the provider says to.
- Turn off data roaming on your UK line so it doesn't use data accidentally.
Keep your UK number working
Keeping your UK SIM active lets you receive texts, including bank security codes. Incoming texts are usually free or cheap, but check your network's roaming charges for calls. Wi-Fi calling, if your network supports it abroad, can let you make and receive calls over Wi-Fi at UK rates. Messaging apps work over any data connection.
Avoid surprise bills
- UK networks must send you a text when you start roaming with information about charges. Read it.
- Be careful on ferries and cruise ships, where phones can connect to maritime or satellite networks charged at very high rates. Use flight mode at sea unless you're sure.
- Turn off automatic app updates and cloud photo backups over mobile data.
- Download offline maps, playlists and entertainment before you go.
- Set a spending cap with your UK network if offered.
How much data do you need?
Maps, messaging and occasional browsing use relatively little. Video calls, streaming and hotspotting use much more. Your phone's settings show how much mobile data you use in a typical week at home, which is a good guide. Topping up is usually possible if you run low.
Security
Using your own mobile data is generally safer than open public Wi-Fi. If you use public Wi-Fi, stick to sites and apps that use encryption, avoid logging into sensitive accounts, and keep your phone's software updated.
Frequently asked questions
Can I use WhatsApp with a travel eSIM?
Yes. WhatsApp stays linked to your UK number and works over any data connection.
Do eSIMs work on flights?
Only if the airline offers in-flight connectivity, which is separate and usually paid.
Sources and further reading
Facts checked on 20 October 2026. Spotted an error? Tell us and we will correct it.