Cheap mobile networks: the same masts, a smaller bill
Here’s the bit the big networks would rather you didn’t dwell on: cheap mobile networks run on exactly the same masts as EE, O2, Three and Vodafone. Same signal, same bars on your phone, often less than half the price. The only real difference is the name on the bill.
By Jordan, mobile and consumer tech writer at Switcheroo. Last updated July 2026.
Yet millions of us stay put on a big name tariff, paying a premium for a network we could rent for less. That’s the Do Nothing Default, and your provider is quietly counting on it. This guide explains how cheap mobile networks work, which big network each one uses, and how to move over in about the time it takes to make a cup of tea.
What are cheap mobile networks and how do they work?
Cheap mobile networks are what the industry calls MVNOs, or mobile virtual network operators. In plain English, they don’t build their own masts. They rent space on one of the four big networks and sell you airtime on it, usually with lower prices and simpler plans.
So when you buy a SIM from giffgaff, your calls and data travel over O2’s network. Buy from Smarty and you’re on Three. The mast on the hill has no idea which brand sold you the SIM, and it doesn’t care. That’s why a budget SIM can give you the same coverage a big network charges a lot more for. As a rough rule, the resellers sell the same airtime for somewhere around 30 to 50 per cent less than the host network charges under its own name.
Most cheap mobile networks sell SIM only plans on 30 day rolling terms, so you’re not tied in for two years. If you’re weighing up whether that suits you, our guide to SIM only or a phone contract breaks down the trade offs.
Which big network does each cheap SIM use?
This is the part worth bookmarking. Here’s who runs on what, checked July 2026. One thing to note: Vodafone and Three merged into a combined group in 2025, but both networks and their budget brands still operate as before.
| Cheap network | Runs on | 5G included | Worth knowing |
|---|---|---|---|
| Smarty | Three | Yes, on all plans | Simple rolling plans, owned by Three |
| iD Mobile | Three | Yes | Frequent introductory offers |
| giffgaff | O2 | Yes on most plans | Flexible monthly “goodybags”, no contract |
| Tesco Mobile | O2 | Yes in many areas | Around 99% UK 4G coverage, Clubcard perks |
| Lebara | Vodafone | Yes | Low introductory prices, strong on data |
| Voxi | Vodafone | Yes | Some plans throw in social media data |
Prices move around constantly and introductory deals come and go, so treat any specific figure as a rough guide and compare live before you buy. The pattern that doesn’t change is the important one: a cheap mobile network gives you a big network’s coverage without a big network’s price tag.
Do you get worse coverage on a cheap mobile network?
Mostly, no. A cheap mobile network uses its host’s masts, so your coverage map is basically the host network’s map. A Smarty SIM sees the same Three signal a full price Three SIM does. Same towers, same bars.
There are a couple of honest caveats. A few budget brands can deprioritise your data when a mast gets busy, so speeds may dip at peak times in crowded places. And some extras, like WiFi calling, the newest 5G bands or roaming perks, vary by brand. Before you switch, it’s worth a two minute check on the free Ofcom coverage checker for your postcode, using the host network shown in the table above.
How much could you save with a cheap mobile network?
It depends on your current deal and how much data you use, so treat any figure as an estimate. But the gap is often wide. A mainstream big network plan with a decent data allowance can sit north of around £15 to £20 a month, while a comparable cheap mobile network SIM with the same sort of data is frequently in the region of £6 to £10 (checked July 2026).
On those rough numbers, moving over could save somewhere around £8 to £12 a month, which is roughly £100 to £140 a year for changing very little about how you use your phone. Your own saving depends on your usage and the deal you pick, so the only way to know your number is to compare live prices for your data allowance.
The maths is simple once you see it. You aren’t paying for a worse network. You’re paying less for the same network, minus the marketing spend and the two year lock in.
Why now: the big networks just put their prices up
Every April, the big networks raise prices mid contract. From April 2026, EE added around £2.50 a month to many SIM only plans taken out after July 2025, and O2 raised some plans by up to about £2.50 a month too (checked July 2026). Vodafone’s fixed rises work the same way, a set amount in pounds and pence added each year.
Those rises are now spelled out up front, a change Ofcom brought in from 2025. But clearer hasn’t meant cheaper. Research by MoneySavingExpert in June 2026 looked at more than 47,000 tariffs and found roughly three in four customers end up worse off under the new pounds and pence system than under the old inflation linked one.
Here’s the off ramp. Many cheap mobile networks sell 30 day rolling SIMs with no fixed annual rise locked in, so you can leave whenever you like. Always check a provider’s own terms, but the flexibility is the point: doing nothing has a price, and switching is the fix. Switcheroo is rated 4.45 out of 5 on Reviews.io by people who’ve done exactly that.
How to switch to a cheaper mobile network
Switching is quick, free and keeps your number. Here’s the short version:
- Text PAC to 65075 from your current phone. Your network has to send your porting code straight back, for free.
- Pick your new cheap mobile network and order a SIM or eSIM.
- Give the new provider your PAC. Your number moves across, usually within one working day.
There’s no need to ring anyone or explain yourself. For the full walk through, see our guide on how to switch and keep your number, and if you want to see live budget SIM prices side by side, our SIM only deals guide is a good place to start.
Key takeaways
- Cheap mobile networks (MVNOs) run on the same masts as EE, O2, Three and Vodafone.
- Smarty and iD Mobile use Three; giffgaff and Tesco Mobile use O2; Lebara and Voxi use Vodafone.
- Coverage broadly matches the host network, so check its map for your postcode first.
- Many budget SIMs are 30 day rolling, so there’s no long tie in and no fixed annual rise locked in.
- Text PAC to 65075 to keep your number when you switch.
Frequently asked questions about cheap mobile networks
- Are cheap mobile networks any good?
- Yes, for most people. They use the big networks’ masts, so coverage is broadly the same, and plans are usually cheaper and more flexible. The main trade offs are occasional data deprioritisation at busy times and fewer extras on some brands.
- Which cheap network has the best coverage?
- It depends on where you live, because coverage follows the host network. Check the Ofcom coverage checker for the host network (Three, O2 or Vodafone) at your postcode before you choose.
- Can I keep my phone number if I switch?
- Yes. Text PAC to 65075, give the code to your new provider, and your number moves across, usually within a working day.
- Do cheap mobile networks have 5G?
- Most now include 5G at no extra cost, though it can depend on the plan and your handset. Smarty, iD Mobile, giffgaff, Lebara and Voxi all offer 5G on many plans (checked July 2026).
- Will my bill go up mid contract?
- Many budget SIMs are 30 day rolling with no fixed annual rise, so you can leave any time. Always check the individual provider’s terms, as policies differ.
