Network vs network
O2 vs Three
Different masts, different deals. We compare price rises in pounds, roaming, credit checks and today’s cheapest SIMs on both.
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Do they use the same masts?
No. O2 uses its own masts and Three uses its own masts. Check coverage at home and work for both.
Which one raises prices?
O2: +£2.50 every April. Three: +£1.80 to £2.30 every April by data.
Which is better abroad?
O2: EU included, 25GB. Three: Go Roam £2.75 a day unless included.
O2£228
Three£285.60Cheapest SIM with 10GB or more × 24, plus April rises
Live prices; rises estimated for a plan starting this month.
Over 24 months, the cheapest 10GB+ SIM costs £228 on O2 and £285.60 on Three once April rises are added — O2 is £57.60 cheaper. O2 runs on its own masts; Three on its own masts.
Prices checked 28 October 2026 · facts checked monthly · How we compare
O2 vs Three, side by side
| O2 | Three | |
|---|---|---|
| Masts | Own masts | Own masts |
| Annual price rise | +£2.50 every April | +£1.80 to £2.30 every April by data |
| Roaming | EU included, 25GB | Go Roam £2.75 a day unless included |
| Credit check | Hard check | Hard check |
| eSIM | Yes | Yes |
| Wi-Fi Calling | Yes | Yes |
| Ofcom complaints per 100k (Q1 2026) | 3 | 2 |
| Cheapest SIM, 10GB+ | £7 a month | £7 a month |
| Cheapest SIM, 30GB+ | £8 a month | £8 a month |
| Cheapest SIM, Unlimited | £23 a month | £12.42 a month |
Highlighted = better on that line. Facts from network terms and Ofcom; prices live.
Our verdict
On price, O2 comes out ahead for a typical 10GB+ SIM: £57.60 less over two years once April rises are counted (O2 rises add about £60, Three’s about £45.60).
Coverage differs: O2 uses its own masts and Three uses its own masts. Check both on the mast owner’s postcode checker for home and work before you decide.
Pick O2 if…
- You want the lower 24-month cost for a 10GB+ SIM
- O2’s own masts are strongest where you live
O2 and Three SIM only deals, live
FAQ
O2 vs Three questions
Is O2 or Three cheaper?
O2, today: the cheapest 10GB+ SIM costs £7 a month, and over 24 months with April rises the gap is £57.60.
Do O2 and Three use the same network?
No. O2 uses its own masts and Three uses its own masts.
Which has better roaming?
O2: EU included, 25GB. Three: Go Roam £2.75 a day unless included.
Can I switch from O2 to Three and keep my number?
Yes. Text PAC to 65075 from your O2 phone, give the code to Three, and the number moves within one working day.