O2 review
Updated September 30, 2026 · TariffCue Editorial Team · Facts checked September 30, 2026
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Our verdict
O2 suits UK households who want sim only lines, several lines on a single bill and eSIM and 5G included, with roaming across 48 countries. The trade-off sits in billing, which runs contract and prepaid, so anyone wanting rolling monthly payments will find more room at yesss!.
Key facts
- Best for
- Households buying several sim only lines on a single account.
- Seller type
- Network (Source, checked September 30, 2026)
- SIM-only
- Yes (Source, checked September 30, 2026)
- 5G
- Yes (Source, checked September 30, 2026)
- eSIM
- Yes (Source, checked September 30, 2026)
- EU roaming
- Fair use (Source, checked September 30, 2026)
- Roaming countries
- 48 (Source, checked September 30, 2026)
- Data rollover
- Yes (Source, checked September 30, 2026)
- Multi-line discount
- Yes (Source, checked September 30, 2026)
- Legal entity
- Telefonica UK Limited (Source, checked September 30, 2026)
- Headquarters
- United Kingdom (Source, checked September 30, 2026)
- Support channels
- Phone, Chat, Help-centre, Community (Source, checked September 30, 2026)
- Billing
- Contract, Prepaid
- Official website
- o2.co.uk
Pros and cons
Pros
- Sim only lines let you keep the handset you already have instead of buying with the tariff.
- Unused data rolls over, so an allowance left at the end of a cycle is not wasted.
- eSIM and 5G are available rather than sold as paid extras.
- A multi line discount applies, which matters for a household with several lines.
- Roaming reaches 48 countries, on fair use terms.
Cons
- Billing runs contract and prepaid, which leaves out the rolling monthly option listed in contract, rolling and prepaid.
- EU roaming works on fair use terms across 48 countries, so heavy use abroad needs checking.
- Support runs phone, chat and help centre, so email is not among the ways to reach the operator.
- Buying from a network operator, network, means there is no reseller tariff to weigh, unlike Astound at reseller.
Who it suits
- Households running several lines on a single bill who want the discount built in.
- Sim only buyers bringing a handset they already own, with eSIM where the phone supports it.
- Regular travellers to Europe who stay inside fair use and prefer a network operator rather than a reseller.
Who should look elsewhere
- Anyone who needs rolling monthly billing, because yesss! lists contract, rolling and prepaid and O2 bills contract and prepaid.
- Buyers who would rather not contract with the network itself, since Astound sells as reseller while O2 sells as network.
- Anyone treating prepaid as the deciding factor, since GETESA lists prepaid and contract and O2 lists contract and prepaid.
What it does well
O2 covers the everyday needs of a UK household without much fuss. Sim only lines mean a handset can be brought along rather than bought with the tariff, which suits anyone replacing a phone on its own schedule. Data rollover is part of the range, so an allowance left at the end of a cycle carries into the following cycle rather than disappearing. eSIM is available for compatible phones and 5G runs on the network, so neither depends on a paid add on. Households running several lines can use the multi line discount to soften the total. Roaming reaches 48 countries, which covers the usual European trips.
Who runs it
O2 is the trading name of Telefonica UK Limited, the UK business behind the brand, and it sits in the United Kingdom. Contracts are taken with the operator itself rather than through a broker, so the account sits with the company that runs the network. Support runs on phone, chat and help centre: a call or a chat reaches an agent, a help centre covers the questions worth looking up yourself, and a community forum lets other customers answer the rest.
How O2 compares
Budget Thuis Mobile
EE Store is also on the sim-only deals list and sells in the same markets, with prices from £26.99.
Frequently asked questions
Can I take a sim only line from O2?+
Sim only lines are part of the O2 range, so you can bring your own handset. Billing runs contract and prepaid, which gives a contract line or a prepaid line. O2 sells as network, so the tariff is issued by the network operator itself rather than by a reseller, which matters if you want a direct relationship.
How does EU roaming work on an O2 plan?+
Roaming is the part to read carefully. EU usage runs on fair use terms, and the network covers 48 countries for it. Fair use is not the same as unlimited roaming, so anyone streaming or browsing heavily while travelling should check the limits before booking a long trip abroad.
Does O2 offer eSIM and 5G?+
Both are available. eSIM is supported, so a compatible handset can be set up without a plastic card, and 5G runs on the network, so neither depends on a paid extra. That matches the wider picture: 100% of the eSIM listings tracked here offer eSIM, and 92.7% of network plans carry 5G.
What happens to data I do not use?+
Unused data rolls over, so an allowance left at the end of a cycle is carried into the following cycle rather than lost. That habit is common across the plans listed here, with rollover on 71.1% of them. It is among the easier ways to stop paying for data you never touched.
Is there a discount for several lines?+
Yes, a multi line discount applies, which suits a household running several lines on a single bill. Discounts of this kind sit on 98.1% of the plans tracked here, so it is common rather than unusual. Billing still runs contract and prepaid, so it is worth asking how the discount applies to a prepaid line as well as a contract line.
Who do I deal with and how do I get help?+
You are contracting with Telefonica UK Limited, the UK operation behind the O2 brand, and the business is based in the United Kingdom. Help comes through phone, chat and help centre. In practice a call or a chat handles most questions, a help centre covers anything you would rather look up yourself, and a community forum carries peer answers.
How does O2 compare with rolling billing at yesss! and GETESA?+
That is the sharpest difference between them. O2 billing runs contract and prepaid, so contract and prepaid are the options. yesss! lists contract, rolling and prepaid, which adds rolling monthly billing, and GETESA lists prepaid and contract. If paying month to month without a fixed term matters, yesss! has the edge on the facts above.
Is O2 a network operator or a reseller?+
O2 sells as network, which means it issues the tariff itself and you deal with the company that builds the network. Astound, by contrast, sells as reseller, so its plans sit on someone else's network. Most of the mobile network listings here are network sellers too, at 100%.
Sources
- o2.co.uk checked September 30, 2026
Backs: Billing, Headquarters, Legal entity, Multi-line discount
“SIM Only Deals, Pay As You Go SIMs”
- o2.co.uk/5g checked September 30, 2026
Backs: 5G, Seller type
“All our plans come with 5G”
- o2.co.uk/contactus checked September 30, 2026
Backs: Support channels
“You can always give us a call or chat to us online”
- o2.co.uk/data-rollover checked September 30, 2026
Backs: Data rollover
“Data rollover lets you take any of your main data allowance left over”
- o2.co.uk/eu-roaming checked September 30, 2026
Backs: EU roaming, Roaming countries, SIM-only
“roam freely in the EU at no extra cost, up to 25GB”
- o2.co.uk/help/phones-and-devices/sims-and-numbers/esim checked September 30, 2026
Backs: ESIM
“Yes - O2 supports eSIM on compatible smartphones”
Compiled from 6 source pages, checked September 30, 2026. We did not open an account.
Not confirmed yet: Price from, Reference plan prices, Unlimited plan price, Contract length.