Bottom line: Choosing a UK SIM card comes down to two things that have nothing to do with price or where you buy it: which network the brand actually runs on, and whether your handset can make calls over 4G. Every UK 3G network is now switched off. Three has no 2G network at all, so on Three an older handset cannot call, text, or use data. And Ofcom, the regulator, publishes exactly which network each budget brand sits on.
If you would rather settle the device question before you fly, an eSIM installs at home. You can size a plan to your trip from Coral eSIM's UK plans.
UK 3G is already gone
The country now runs on 2G, 4G and 5G
Ofcom's current guidance states it plainly: "3G mobile networks are now switched off." It then describes the UK as using "three different 'generations' of mobile technology: 2G, 4G and 5G."
Plenty of travel advice still assumes 3G is there as a fallback. It is not. If your handset does not support 4G, that is not a question of slower speeds — it is a question of whether it connects at all.
On Three, an older handset is completely dead
This is the detail most guides miss, and Ofcom is explicit that the answer differs by network.
- EE, Vodafone and O2: an older device can still make calls and send texts over 2G. But 2G was never designed for data, so with 3G gone those customers can no longer access most mobile data services
- Three: has no 2G network at all. On a handset without 4G or 5G, calls, texts and data all fail. Ofcom's advice is to replace the device
So two SIMs sold side by side in the same shop can impose completely different device requirements. Pick the cheapest plan, land on a Three-based brand with an old handset, and the phone simply goes silent.
Even a 4G phone may need a settings update
Ofcom adds a caveat for 4G devices too: "Some 4G devices might still need a software or settings update to ensure any calls you make use the right network." That is calling over 4G — VoLTE.
This is the failure mode where data works perfectly but calls do not connect. If you are bringing an older phone as a travel handset, it is worth checking before departure. See using an eSIM on an older iPhone, eSIM device compatibility, and whether your phone is carrier-unlocked.
To settle all of this before you travel, Coral eSIM's UK plans install at home; the steps are in our travel eSIM setup guide.
2G is going too, and the dates are published
Calls and texts over 2G are a temporary reprieve. All operators have committed to Government to switch off 2G by 2033 at the latest, and the individual timetables are already public.
| Operator | 2G switch-off |
|---|---|
| EE | Nationwide retirement from May 2029 (announced October 2025) |
| Virgin Media O2 | Starting Summer 2029 |
| VodafoneThree (Vodafone network) | Spring 2030 |
| Three | Has no 2G network to switch off |
| All operators | By 2033 at the latest |
In March 2026 the Government also published a voluntary 2G switch-off charter setting out operator commitments to support the transition. None of this is imminent, but if you are relying on 2G for calls today, it is a reprieve with an expiry date on it.
Ofcom publishes which network each brand runs on
The regulator names them directly
Most visitors are sold a budget brand rather than one of the network operators. Ofcom lists which network each of those brands uses (as published on 10 August 2026).
| Network | Brands running on it |
|---|---|
| EE | Your Co-op, 1p Mobile, Utility Warehouse, Ecotalk, Lycamobile, BT Mobile |
| Vodafone | Lebara Mobile, Asda Mobile, Talk Mobile, VOXI |
| O2 | Tesco Mobile, Giffgaff, Sky Mobile |
Ofcom also notes that "2G switch-off timings for these providers will be the same as the network they are using." Choosing a brand is choosing a network, whether or not the marketing says so.
There are no longer four networks to choose between
Guides still frame the UK as "EE, Vodafone, O2 and Three." Vodafone and Three have merged into VodafoneThree. Government publications now use the VodafoneThree name, and Ofcom explains in a footnote that "Vodafone and Three submitted separate datasets for coverage predictions, and we will continue to report on their networks separately until they are fully integrated."
In practice this is a transitional state: two radio networks, one company. When comparing plans, the reliable question is not whose brand it is but which network in the table above it sits on.
Outside the cities, the network choice starts to matter
Ofcom publishes coverage based on signal-strength predictions submitted by the operators. As of January 2026:
- Good 4G from all operators: 84% of UK landmass (up three percentage points)
- 4G from at least one operator: 96%
- Coverage outside premises: at least 99% for every operator
- 5G overall: 76% to 94% per operator; 64% from all operators
- 5G standalone: 49% to 85% across the three operators that have deployed it
The gap between 84% and 96% is precisely where your network choice shows up. In central London or Manchester, any brand performs much the same. The difference appears in the Scottish Highlands, rural Wales, and Cornwall. If your itinerary involves trains or a hire car outside the big cities, pick by network rather than by brand.
Ofcom provides a coverage checker that takes a postcode and shows results by operator. If you already know where you are staying, you can check before you fly. For diagnosing a slow connection, see what to check when mobile data is slow.
A UK SIM does not roam free across the EU
One more thing that changes itineraries. "Roam like at home" is an EU scheme, and the UK is not an EU member state.
Per the European Commission, within the EU you pay domestic rates with no surcharge, and under the fair use policy the data ceiling is EUR 1.30 per GB plus VAT in 2025, dropping to EUR 1 plus VAT from 2027. On a prepaid card you are guaranteed at least your remaining credit divided by EUR 1.30 in roaming data. Those protections attach to SIMs from EU member states.
Ofcom's own guidance treats the EU no differently from anywhere else: "Mobile phone companies must publish their roaming charges on their website." The price is whatever the provider sets.
So if your trip spans the UK and continental Europe, a UK SIM does not settle the continental leg — check that separately. A SIM bought in an EU country does travel across the bloc (covered in buying a local SIM card in Italy). For the wider comparison see roaming versus eSIM.
Worth noting: Ofcom itself lists, among its money-saving tips, "you might want to buy a SIM card for the country you are visiting or an 'e-SIM'." Buying locally is a regulator-endorsed option.
FAQ
Does 3G still work in the UK?
No. Ofcom states that "3G mobile networks are now switched off" and describes the UK as running on three generations: 2G, 4G and 5G. A handset without 4G support can no longer reach mobile data through 3G.
Will my older phone work in the UK?
It depends on the network. On EE, Vodafone and O2, an older device can still make calls and send texts over 2G, but because 2G was not designed for data, most mobile data services are no longer available to it. Three has no 2G network, so on a handset without 4G or 5G, calls, texts and data all fail. Ofcom also warns that some 4G devices need a software or settings update so that calls use the right network.
Which network do giffgaff and Lycamobile use?
Per Ofcom's published list, Giffgaff, Tesco Mobile and Sky Mobile use the O2 network; Lycamobile, BT Mobile, 1p Mobile, Utility Warehouse, Your Co-op and Ecotalk use EE; and Lebara Mobile, Asda Mobile, Talk Mobile and VOXI use Vodafone. Ofcom adds that each brand's 2G switch-off timing matches the network it uses. The list is updated, so check the current version before buying.
Are there still four mobile networks in the UK?
Not as companies. Vodafone and Three have merged into VodafoneThree, and Government publications use that name. Ofcom continues to report the Vodafone and Three networks separately because they submitted separate datasets and are not yet fully integrated. Compare by which network a plan runs on rather than by operator name.
Does a UK SIM card work in the EU without extra charges?
Not automatically. "Roam like at home" is an EU scheme and the UK is not an EU member state, so UK SIMs are outside it. Ofcom's guidance does not treat the EU differently from other destinations; providers set and publish their own roaming charges. Check the terms for the continental leg of your trip separately.
Pick a UK SIM card by the network underneath it and the generation your phone supports
Most guidance on UK SIM cards is still written around a 2020-era frame: four networks, pick the cheapest, buy it at the airport. The primary sources show two structural changes since then. Every 3G network has been switched off, and Vodafone and Three have merged. Both are documented by the regulator and the Government.
That reorders the decision. First, can your handset make calls over 4G. Second, which network does the brand actually run on. Third, if you are leaving the cities, what is that network's coverage where you are going. Price comes after all three. The Three-based option in particular carries a stricter device requirement than its neighbours on the shelf, and nobody at the till will mention it.
If you want the device question closed before departure and data working the minute you land, install before you fly. Coral eSIM's UK plans set up at home and connect on arrival, and the full plan list covers other stops on the same trip. If nothing connects, work through eSIM not working on arrival and APN settings.