FACT · UK MOBILE NETWORK OPERATOR
O2 (UK)
Updated May 14, 2026 · By Jules de Bruin · UK mobile network operator profile.
Updated May 2026. O2 UK is the second-largest mobile network operator in the United Kingdom by subscribers, operated by Virgin Media O2 - a 50/50 joint venture between Liberty Global and Telefónica. O2 hosts the wholesale traffic for Tesco Mobile, giffgaff and Sky Mobile, runs the Priority ticket and rewards programme with 48-hour pre-sale access at The O2 and AEG venues, and bundles a Disney+ perk on selected pay-monthly tariffs. SIM-only starts from GBP 15/month with 25 GB EU roaming via the Europe Zone.
What is O2 UK?
O2 UK is one of the United Kingdom's four mobile network operators (MNOs), running its own nationwide 2G/4G/5G radio access network under the Virgin Media O2 corporate umbrella. It sits in the number-two or number-three slot by subscribers depending on the quarter, behind EE and roughly tied with Vodafone, and it wholesales capacity to several of the country's biggest budget brands.
The network traces its lineage to BT Cellnet, launched in 1985 as one of the UK's original two cellular networks. It was rebranded O2 in 2002 after BT spun out its mobile arm as mmO2. Telefónica, the Spanish telecoms group, acquired O2 plc in 2006 for GBP 17.7 billion and operated the brand as Telefónica UK for fifteen years.
In June 2021, Telefónica UK merged with Liberty Global's Virgin Media to form Virgin Media O2, a 50/50 joint venture headquartered in Slough. The combined business serves around 47 million mobile, broadband and TV connections in the UK and competes directly with the BT Group (which owns EE) and the merged Vodafone-Three entity.
O2's commercial identity rests on three pillars consumers see daily: Priority, the loyalty app that gives 48-hour pre-sale access to gigs at The O2 arena and other AEG venues plus rotating high-street offers; the Disney+ perk bundled on selected Volt and pay-monthly tariffs; and the Europe Zone roaming benefit that keeps 25 GB of EU data included on most consumer plans despite Brexit. The operator also runs O2 Open, a corporate discount programme offering 10-20% off SIM-only to eligible employees of partner companies.
Key facts
The figures below summarise O2's corporate structure, network footprint and headline consumer pricing as published by the operator and tracked by Opensignal and Ofcom through May 2026.
How does O2 compare to EE/Vodafone/Three?
O2 sits in the middle of the UK Big Four: Opensignal rates EE highest for overall download speed and rural coverage, but O2 leads London 5G availability at 77.8%. Versus Vodafone, O2 ships the more generous Europe Zone roaming bucket; versus Three (now merged into Vodafone Three UK), O2 is typically more expensive headline but bundles richer perks.
On coverage, EE consistently wins national connect/RootMetrics rankings, particularly in rural Scotland and Wales. O2 trades blows with Vodafone for second place and is strongest in dense urban centres - especially London, where Opensignal's 2025 5G report put O2 first on availability ahead of EE's 76.4% and Vodafone's sub-70%.
On price, the cheapest unlimited SIM-only plans from SMARTY (Three) and iD Mobile (Three) undercut O2's direct pricing by GBP 5-10/month. O2 differentiates with Priority, the Disney+ perk on Volt tariffs, and the Europe Zone 25 GB allowance - none of which the discount MVNOs ship.
On roaming, O2 is the most generous of the Big Four post-Brexit: 25 GB Europe Zone roaming included on most consumer plans, vs Vodafone's daily fee model and EE's fair-use cap on cheaper tariffs.
Where does O2 appear on SimCompare365?
O2 is referenced across the UK hub - on the master provider comparison, the dedicated O2 plan page, the EE-vs-O2 London comparison, and on every MVNO page hosted on the O2 network (giffgaff, Tesco Mobile, Sky Mobile, Lyca Mobile).
Sources
Primary sources for this page are the operator's own tariff and corporate communications, plus Ofcom's mobile market reports and Opensignal's UK 5G measurement studies.
Frequently Asked Questions
Which MVNOs run on the O2 network?expand_more
The three highest-volume MVNOs on O2 are Tesco Mobile (Clubcard perks, owned 50/50 by Tesco and Virgin Media O2), giffgaff (community-run, sub-GBP 10 PAYG goodybags) and Sky Mobile (bundled with Sky TV). Lyca Mobile also routes part of its UK traffic through O2 for international calling plans.
What is O2 Priority and is it free?expand_more
Priority is O2's loyalty app, free for any O2 or giffgaff customer. The headline benefit is 48-hour pre-sale ticket access for The O2 arena, The O2 Institute venues and other AEG-managed shows, plus rotating high-street offers (cinema, coffee, food chains). No separate subscription fee is charged.
Does O2 still offer free EU roaming after Brexit?expand_more
Yes. Unlike Vodafone and EE, O2 kept inclusive EU roaming on most consumer pay-monthly and SIM-only plans via its Europe Zone - covering the EU-27 plus Iceland, Liechtenstein, Norway and a handful of other destinations. The standard fair-use cap is 25 GB of mobile data per month while abroad.
How good is O2 5G coverage outside London?expand_more
London is O2's standout city with 77.8% 5G availability per Opensignal. Outside the capital, O2 5G covers all major UK cities plus the south-east commuter belt and substantial parts of the Midlands and northern England. EE still leads on rural and Scottish coverage, so O2 is best paired with a check on its official coverage map before relocating.
How does the O2 Disney+ perk work?expand_more
Selected O2 pay-monthly and Volt tariffs (the cross-product bundle for Virgin Media broadband + O2 mobile customers) include Disney+ as a switchable Extra. The perk runs for the length of the contract; if you cancel the SIM, the Disney+ subscription stops or reverts to direct billing. Eligibility is plan-specific and shown at checkout.