What network does giffgaff use?

giffgaff runs on O2's network, as do Tesco Mobile and Sky Mobile. Your giffgaff coverage is O2 coverage — though 5G+ access and busy-hour priority can differ from a direct O2 contract.

What network does Smarty use?

Smarty is Three's own budget sub-brand, running on the Three network. iD Mobile also uses Three. Superdrug Mobile closed in 2025.

Are piggyback networks slower than the real network?

Often, yes — in two ways. Many MVNOs don't get the host's fastest 5G+ (standalone) layer, and at congested times hosts can prioritise their own direct customers. At quiet times in strong-signal areas you'll rarely notice a difference.

Do I keep my number if I switch to a piggyback network?

Yes. Text PAC to 65075 for a porting code from your old provider and give it to the new one — the switch typically completes in one working day, and it works across any UK networks.

← Piggyback Checker

What network does my SIM actually use? The UK piggyback map

Written by the team behind the Piggyback Checker. Updated 18 August 2026.

There are only four mobile networks in the UK: EE, Three, Vodafone and O2. Every other name you've seen — giffgaff, Smarty, Tesco Mobile, Voxi, Lebara, iD Mobile, and dozens more — is a piggyback network (an MVNO), renting space on one of those four. Which host your SIM rides determines your coverage completely. The badge on the SIM determines your price. Knowing both is how you get the good network for the cheap price.

The map: who runs on what

On EE: 1pMobile, BT Mobile, Plusnet Mobile, Lycamobile, Utility Warehouse
On Three: Smarty (Three's own budget brand), iD Mobile, Honest Mobile
On Vodafone: Voxi (Vodafone's own), Lebara, Talkmobile, Asda Mobile
On O2: giffgaff, Tesco Mobile, Sky Mobile, Virgin Media O2 brands

Some names have moved over the years (Asda was once EE; Virgin Mobile was once Three) — which is why "my mate gets great signal on X" is unreliable folklore if their SIM predates a host migration.

What piggybacking costs you

MVNOs are cheaper for real reasons, and the small print is speed. Two mechanisms matter. First, 5G+ access: the hosts' fastest standalone-5G layer is often reserved for their own direct customers — most MVNOs get "ordinary" 5G at best. Second, deprioritisation: when a mast is at capacity, hosts can serve their own customers first. On a quiet Tuesday in a strong-signal suburb you will never notice either. At a festival, a football ground, or a busy commuter station at 6pm, you might.

The trade is usually worth it: half the price for 90% of the experience. But make the trade knowingly — and pick the MVNO whose host is actually the best network at your address, which is precisely the thing nobody checks before buying a SIM because it says £8/month.

How to choose in two minutes

1) Check which of the four hosts is strongest at your postcode (our checker ranks them with Ofcom data). 2) Pick the cheapest MVNO riding that host. 3) Keep your number: text PAC to 65075, give the code to the new provider, done in a working day. If two hosts tie at your address, let price break the tie — that's the piggyback game played correctly.

Check your address: the Piggyback Checker ranks all four host networks at your postcode and lists every MVNO on each — so you buy the cheap SIM that happens to be on the right network.

Host relationships correct as of August 2026; MVNOs occasionally migrate hosts. Provider links on our tools are affiliate links; the best option always ranks first even when it pays us less, or nothing.