To use your phone in London you have three choices: roam on your home plan, buy a UK SIM card, or install an eSIM with a data package. Which is cheapest depends on your home operator, how long you stay and whether you need a UK phone number. EU visitors should note that the EU's "roam like at home" rules do not cover the UK.
A working phone makes a London trip much easier. You use it for maps, for paying fares with contactless, for booking tickets and restaurants, and for calling a minicab or NHS 111. Being without data for a day or two is manageable, because many places offer Wi-Fi, but most visitors want a connection from the moment they land.
This guide explains the three options in plain terms, where your phone will and will not work on the Underground, what to know about Wi-Fi, and why some older phones may struggle on UK networks. We do not recommend any particular company: prices and packages change often, so compare them yourself before you travel.
Mobile phones in the UK: key facts
- Network operators
- EE, Virgin Media O2 and VodafoneThree (Vodafone and Three brands)
- EU "roam like at home"
- Does not cover the UK; some EU operators include it anyway
- Signal on the Underground
- Whole Elizabeth line; about half of below-ground Tube stations, plus sections of tunnel
- Wi-Fi at stations
- All Tube stations, provided through mobile networks; no Wi-Fi in tunnels
- Older networks
- 2G being switched off between 2029 and 2033; phones need 4G or 5G
- Emergency number
- 999, or 112
Roaming on your home plan
Roaming means using your normal SIM and phone number abroad, on a UK network that has an agreement with your home operator. It is the simplest option: nothing to buy or install, and you keep your usual number for calls, texts and bank security codes. The question is the price.
For visitors from the EU, the key fact is that the UK left the EU's roaming rules. The EU's official Your Europe site says "roam like at home" covers the EU plus Iceland, Liechtenstein, Norway, Moldova and Ukraine, and that the UK is not covered. It also says many operators choose to extend these offers to other countries. So some EU plans include the UK at no extra cost, and others charge per day or per megabyte. Check your own operator's price for the UK before you leave, and turn off data roaming if you are unsure.
Free roaming in France does not mean free roaming in London. If you are an EU customer, your plan's rules for the UK can be completely different from those for other EU countries. Look up "United Kingdom" specifically in your operator's roaming price list, rather than assuming Europe is all the same.
For visitors from the USA, Canada, Australia, Asia and elsewhere, roaming prices vary widely. Some plans include international use or offer a fixed daily pass; others charge high rates per megabyte. A daily pass can be good value for a weekend, but over a week or two it often costs more than a local SIM or an eSIM. Our guide to what a London trip costs helps you put that in the context of your whole budget.
Buying a UK SIM card
A UK pay-as-you-go SIM gives you a British phone number and a package of data, calls and texts for a set period. They are sold in mobile phone shops, and many supermarkets and newsagents also sell SIM cards and top-ups. You simply pay, put the card in your phone and follow the activation instructions.
Before you buy, check two things:
- Your phone must not be network-locked. A phone bought on a contract may be locked to your home operator and will reject a foreign SIM. Ask your operator to remove the lock before you travel.
- You need somewhere to keep your home SIM. While the UK SIM is in your phone, you will not receive calls or texts to your home number, including security codes from your bank. Phones that take two SIMs, or a SIM plus an eSIM, avoid this problem.
A UK number is useful for more than data. Restaurants, tour companies and taxi firms often call or text UK numbers more easily, and booking confirmations reach you without roaming charges. For stays of several weeks, a UK SIM is usually the most practical choice.
If you are arriving at Heathrow, you may want to be connected before you choose a route into town. Our guide to getting from Heathrow to central London compares the Elizabeth line, the Piccadilly line and the Heathrow Express.
eSIMs: a SIM card without the card
An eSIM is a digital SIM built into newer phones. Instead of inserting a plastic card, you install a profile from a QR code or an app. Many travel companies sell data-only eSIM packages for the UK, which you can buy and install at home and switch on when you land.
The advantages are clear. You keep your home SIM active in the phone, so texts and bank codes still arrive, while using the eSIM for cheaper data. You also avoid looking for a shop on arrival. The limits are just as important:
- Your phone must support eSIM and must not be locked to your home network. Check the settings or the manufacturer's information.
- Many travel eSIMs are data only, with no UK phone number. You can still use internet calling apps, but you cannot receive normal UK calls.
- If you delete the eSIM profile by mistake, it may not be possible to reinstall it, so read the seller's instructions.
Install the eSIM at home, switch it on after landing. Setting it up needs a Wi-Fi connection and a few minutes of patience, which is easier on your own sofa than in an arrivals hall. Some packages start their validity period only when the phone first connects in the UK, others on the day you buy, so check the terms.
Which option suits your trip
There is no single best answer. This table sums up the usual reasoning; the final choice depends on the prices your home operator and the sellers offer when you travel.
| Your situation | Usually the best choice | Why |
|---|---|---|
| EU plan that includes the UK at no extra cost | Roaming | No cost, no setup, and you keep your number |
| Weekend trip, reasonable daily roaming pass | Roaming | Simple, and the total for two or three days stays low |
| One or two weeks, newer phone | eSIM | Cheaper data while your home number stays active |
| Several weeks, or you need a UK number | UK SIM card | Local number, local calls, easy to top up |
| Older phone without eSIM, short stay | Roaming or UK SIM | Depends on your operator's UK price |
Families can mix options. One adult with a phone plan that includes the UK can share a hotspot with others for short periods, although this drains the battery quickly.
Mobile signal on the Tube and the Elizabeth line
For years, the Underground was known for having no signal. That is changing. TfL is rolling out 4G and 5G coverage to ticket halls, platforms and tunnels. The whole Elizabeth line now has coverage, with 4G at all stations and 4G and 5G in the tunnels, and TfL says about half of below-ground Tube stations now have signal.
Coverage also runs through sections of tunnel on several lines. TfL's examples include the Central line between Shepherd's Bush and Bank, the Jubilee line between Westminster and Canning Town, the Piccadilly line between Knightsbridge and Holloway Road (except the tunnel between King's Cross and Caledonian Road), and the Victoria line between Brixton and Green Park. On other lines and stretches, expect the signal to drop between stations.
TfL does not charge for this coverage. It comes through your mobile network, so if you are roaming, your normal roaming rates apply. Download the maps and tickets you need before you go underground, just in case. Our Underground guide for visitors explains how the network works, and our page on the Elizabeth line covers the newest and best-connected route.
Wi-Fi in stations, hotels and cafés
TfL says Wi-Fi is available at all Tube stations, most Overground stations, all central London Elizabeth line stations and Victoria Coach Station, though not in the tunnels. Access is provided through mobile networks, under names such as EE WiFi-Auto, Wifi Extra (O2), Three_WIFI and VodafoneWiFi, and The Cloud on the Overground. TfL does not say whether visitors on foreign SIM cards can use it, so do not count on station Wi-Fi as your main connection.
Most hotels offer Wi-Fi to guests, and many cafés, pubs, museums and shopping centres have free networks, sometimes after you register with an email address. Speeds and reliability vary. When you choose where to stay, it is worth checking reviews for Wi-Fi quality if you need to work; our guide to the best areas to stay in London helps with the location itself.
On any public Wi-Fi network, avoid logging in to your bank or entering card details unless the website address starts with https and you trust the network. Using your mobile data for payments is the safer habit.
Older phones and the end of 2G and 3G
UK operators have been retiring their older networks to make room for 4G and 5G. Virgin Media O2 describes its 3G switch-off as complete, and the government says UK mobile network operators will switch off 2G between 2029 and 2033. For a visitor, this matters if you travel with an old or very basic phone.
The government's advice is to check that your phone connects using 4G or 5G, and that 4G calling (sometimes called VoLTE) or 5G calling is switched on in the settings. Most modern phones do this by default. A phone that only works on 3G, or cannot make calls over 4G, may show signal but fail to connect calls. If you rely on an older phone, test it with your operator before you leave, or bring a newer backup.
Your phone as ticket, map and wallet
Many visitors use their phone for almost everything in London: paying fares with a mobile wallet, following walking directions, buying tickets and paying in shops. That is convenient, but it puts a lot of weight on one device.
A dead battery can cost you a maximum fare. If you touch in on the Tube with your phone and it runs out of battery before you touch out, TfL can charge a maximum fare or a penalty fare. You also need to touch in and out with the same device: an iPhone and an Apple Watch count as different ones.
Carry a power bank, charge overnight, and keep a physical contactless card as a backup. Our guide to Oyster, contactless and daily caps explains how paying by phone works, and our page on UK plugs and adaptors covers charging. For card payments more generally, see our guide to money and cards in London.
Maps on your phone make London easy to explore on foot; our guide to walking in London shows where it beats the Tube. But phone snatching is common in busy streets, so step aside before you look at the screen. Our article on staying safe in London explains the risk.
Before you travel, it is also worth installing the apps you will need. The UK ETA app is the official way to apply for the Electronic Travel Authorisation, as our guide to UK entry requirements explains. Save 999 and 111 in your contacts, and read our page on emergency numbers and getting help in case something goes wrong.
Frequently asked questions
Is roaming free in the UK for EU visitors?
Not automatically. The EU's official Your Europe site says "roam like at home" does not cover the UK, although many operators choose to include it. Some EU plans cover the UK at no extra cost and others charge. Check your own operator's price for the UK before you travel.
Should I get a UK SIM card or an eSIM for London?
For a short trip with a newer phone, a data-only eSIM is often the easiest option, and your home number stays active. For a longer stay, or if you need a UK number for calls and texts, a UK pay-as-you-go SIM card is usually more practical. For either, your phone must not be locked to your home network.
Is there mobile signal on the London Underground?
Increasingly, yes. The whole Elizabeth line has 4G, with 5G in its tunnels, and TfL says about half of below-ground Tube stations have signal. Coverage also extends through some sections of tunnel, but on many stretches the signal still drops between stations.
Is there free Wi-Fi on the Tube?
There is Wi-Fi at all Tube stations, but not in the tunnels. TfL says access is provided through mobile networks such as EE, O2, Three and Vodafone. It does not say whether visitors with foreign SIM cards can use it, so do not rely on it as your only connection.
Will my phone work in the UK?
Most modern phones work on UK networks. Check that your phone connects on 4G or 5G and that 4G calling (VoLTE) is on, because UK operators have been switching off older networks. For a UK SIM or a local eSIM, the phone must also be free of any lock to your home network.
Sources
- European Union, Your Europe - Mobile roaming costs (checked September 2026)
- Transport for London - Mobile coverage and Wi-Fi at stations (checked September 2026)
- GOV.UK - Preparing for the 2G switch-off: mobile phones and smart devices (checked September 2026)
- GOV.UK - Telecommunications modernisation: connectivity timeline (checked September 2026)
- Transport for London - Pay as you go (checked September 2026)
- GOV.UK - Get an electronic travel authorisation (ETA) (checked September 2026)