Short answerThe UK has four mobile networks with their own masts: EE (BT Group), O2 (Virgin Media O2), Vodafone and Three. Vodafone and Three merged in 2025 as VodafoneThree and are combining their networks. Every other mobile brand runs on one of these. 3G has been switched off, so 4G is now the base layer for data, with 5G on top.
When this site started in 2012, 4G was brand new and only EE had it. Today 4G is the network everything else leans on. Phones fall back to it, 5G often depends on it, and most routers in cabinets and vans use nothing else.
The four networks
| Network | Owner | Some brands on the same masts | Guide |
|---|---|---|---|
| EE | BT Group | BT Mobile and others | EE data SIMs |
| O2 | Virgin Media O2 | giffgaff, Tesco Mobile, Sky Mobile | O2 data SIMs |
| Vodafone | VodafoneThree | VOXI and others | Vodafone data SIMs |
| Three | VodafoneThree | SMARTY, iD Mobile and others | Three data SIMs |
Brands that rent capacity on another network are called MVNOs. Many business and IoT SIM suppliers are MVNOs too. What matters for coverage is the network underneath, not the name on the SIM.
A short history of UK 4G
- 2012: EE launches the UK’s first 4G network, using spectrum it already held.
- 2013: Ofcom auctions 800MHz and 2.6GHz spectrum. O2, Vodafone and Three launch 4G.
- 2015 onwards: 4G becomes the main data network. Calls start moving to 4G with VoLTE.
- 2019 onwards: 5G launches on top of 4G.
- 2021: O2 and Virgin Media combine as Virgin Media O2. The government and the networks agree that 2G and 3G will close by 2033 at the latest.
- 2024 to early 2026: 3G is switched off. EE and Vodafone finish in early 2024, Three by the end of 2024, and O2 through 2025 into early 2026.
- 2025: Vodafone and Three merge as VodafoneThree.
What VodafoneThree means for data SIMs
The merged company is combining the two networks over several years, sharing masts and spectrum. For SIM buyers, the practical effects so far are gradual: Vodafone and Three SIMs are still sold separately, and both can increasingly use the combined network. If you have kit on either network, nothing needs to change today. When you test a site, testing both is still worthwhile, because they have not fully merged everywhere.
3G is gone; 2G is next
With 3G switched off, devices that only support 2G and 3G lose data. Some older routers, alarm diallers, lift phones and payment terminals fall into this group. Kit that supports 4G is unaffected for data. Voice is the area to watch: 4G calls need VoLTE support in the device and on the SIM. Our 3G and 2G switch-off guide covers what to check.
Which network is best?
National rankings tell you who is best on average. Your router does not live on average. Coverage changes from one side of a valley to the other and from outdoors to the inside of a plant room. Test on site with each network you are considering, ideally at the spot the router will be fitted.
For multi-site estates or equipment that moves, a multi-network SIM or a dual-SIM router spreads the risk across networks.
Checking coverage before you commit
Use two sources and then test on site. Ofcom’s Map Your Mobile checker compares all four networks for a postcode. Each network also publishes its own map. Neither tells you what a router inside a cabinet will see, so put a SIM in a phone or router at the exact spot and read the values with our signal checker.
Frequently asked questions
How many 4G networks are there in the UK?
Four networks own masts: EE, O2, Vodafone and Three. Vodafone and Three are now one company, VodafoneThree, but still run separate brands.
Is giffgaff the same coverage as O2?
giffgaff runs on the O2 network, so coverage is the same. Plans, priorities and features can differ.
Has 3G been switched off everywhere?
EE, Vodafone and Three have switched 3G off. O2 was the last, withdrawing 3G through 2025, with a few areas lasting into early 2026.
When will 2G be switched off?
The government and the networks have agreed that 2G will close by 2033 at the latest. Each network will set and announce its own timetable.
NANick Appleby
Nick Appleby has worked in UK telecoms since 1998, starting at BT, and has spent most of that time on cellular routers, data SIMs and the antennas that connect them for business and industrial sites. He writes 4G SIM to explain how the networks and the kit actually behave, in plain English.