Quick Overview
O2 is part of Virgin Media O2 and is the second-largest UK network by subscribers. Three is operated by CK Hutchison and is the UK's fourth-largest operator, known for aggressive data pricing and an unusually large roaming footprint. Three and Vodafone's planned merger (under regulatory review) could reshape the competitive landscape in 2026–27.
| Category | O2 | Three |
|---|---|---|
| Parent company | Virgin Media O2 | CK Hutchison |
| 4G rural depth | Strong (SRN participant) | Improving (more urban-weighted) |
| 5G cities | 80+ | 150+ |
| APN | mobile.o2.co.uk | three.co.uk |
| Unlimited plans from | ~£20/month | ~£12/month |
| Roaming | EU incl. | Go Roam: 71 destinations incl. |
| MVNOs | giffgaff, Tesco, Sky, Lycamobile | SMARTY, iD Mobile |
Coverage
O2's 4G coverage is strong nationally, with particularly good rural performance thanks to its 800 MHz Band 20 spectrum, which propagates over long distances and penetrates buildings well. Its participation in the government's Shared Rural Network programme has extended its outdoor coverage in rural parts of England, Scotland, Wales and Northern Ireland.
Three's coverage map has improved significantly but remains more urban-weighted. In most UK cities and towns, Three's 4G and 5G signal is excellent. Outside major centres, coverage can be more variable. Three's 5G rollout is actually ahead of O2's by location count (150+ vs 80+), so in cities Three may offer faster 5G speeds.
Data Speeds
Average 4G speeds are comparable — 25–40 Mbps on both networks under normal conditions. Three's 5G, where available, delivers competitive city-centre speeds of 150–400 Mbps. O2's 5G is slower to roll out but delivers good performance in its covered areas. For 4G-dependent users outside cities, O2's network tends to be more reliable.
Plans & Pricing
Three is the cheaper network for unlimited data. SIM-only unlimited plans start from around £12–16/month on Three, versus £20–25/month on O2. Three's pricing structure is simple and data-generous. O2 is pricier but offers the Priority rewards programme, which can justify the premium for users who regularly use it for free coffees, concert tickets and discounts.
APN Settings Compared
| Setting | O2 | Three |
|---|---|---|
| APN | mobile.o2.co.uk | three.co.uk |
| Username | o2web (or blank) | (none) |
| Password | password (or blank) | (none) |
| MCC / MNC | 234 / 10 | 234 / 20 |
| MMSC | http://mmsc.mms.o2.co.uk:8002 | http://mms.three.co.uk:10021/mmsc |
| MMS Proxy | 82.132.254.1 | 212.137.86.109 |
| MMS Port | 8080 | 8799 |
Full guides: O2 APN settings · Three APN settings
Roaming
O2 includes EU roaming at no extra charge on most plans. Three's Go Roam is substantially more generous, covering 71 destinations worldwide including the USA, Australia, New Zealand, Hong Kong, Singapore, and most popular European and holiday destinations. If you travel beyond Europe, Three's roaming advantage is significant.
⭐ Verdict
O2 is the better all-rounder for UK-based users who need reliable rural coverage and value loyalty perks. Three is the winner for frequent travellers, heavy data users and anyone who wants uncapped data at the lowest possible price. Three's international roaming package is arguably the best value of any UK operator.