According to SIM Only Finder's analysis of Ofcom's Mobile Matters 2026 report, EE scored 85%, followed by Three (82%), Vodafone (81%), and O2 (77%). The report benchmarks UK mobile network performance using crowdsourced Opensignal data collected between August 2025 and July 2026.

Across the UK, networks provided a good-quality connection 81% of the time, which Ofcom said "falls short" of its 90% target. The report measures how often a mobile connection meets Ofcom's "good quality" threshold.

UK and National Performance Scores

EE scored highest at 85% across the UK. However, no network met Ofcom's 90% benchmark.

According to the report, most shortfalls came from failing speed thresholds rather than high latency issues. The type of connection made a substantial difference: 4G averaged 78%, while both 5G Standalone and 5G Non-Standalone averaged 92%. However, 4G still handled most data connection attempts, accounting for 75% in England and Northern Ireland, 78% in Scotland, and 82% in Wales.

Ofcom linked much of the variation between areas and nations to differences in 5G access.

Regional Performance Varies Dramatically

Performance differs across the home nations. England saw EE lead at 85%, followed by Three (83%), Vodafone (82%), and O2 (77%), with an all-network average of 82%. Scotland showed EE at 83%, Three at 80%, Vodafone at 79%, and O2 at 76%, averaging 79% across all networks. Northern Ireland had EE at 82%, Vodafone at 83%, Three at 79%, and O2 at 80%, averaging 81%. Wales shows EE at 82%, Three at 78%, Vodafone at 77%, and O2 at 65%, averaging 76%.

O2's 65% score in Wales is the lowest network score in the report—17 points behind EE. O2 also showed the greatest variation between nations, ranging from 65% in Wales to 80% in Northern Ireland.

Rural areas show different performance patterns. The UK average fell to 75% in rural areas, compared with 82% in urban areas. No local authority in the UK met Ofcom's 90% benchmark. West Devon scored lowest at 68%, while Watford achieved the highest at 88%.

What This Means for UK Consumers

Network quality is one of the main reasons people choose a SIM-only deal, and this report provides independent performance data. Consumers in Wales, rural areas, or specific local authorities should consider regional and local performance figures rather than relying solely on UK-wide averages.

Many budget SIM-only brands operate on the major networks as MVNOs. According to the report, Giffgaff and Sky Mobile run on O2's infrastructure, and a brand typically shares its host network's coverage. Customers should verify which underlying network a provider uses before committing to a plan, as provider arrangements can change.

For those uncertain about network suitability, a 30-day SIM-only deal allows testing at home and work without long-term commitment. Customers can also check coverage at their postcode using each network's own coverage checker and ask neighbours about their real-world experience before deciding.

O2 customers in Wales in particular may want to verify local coverage before taking on a new plan.

Crowdsourced Data and Real-World Usage

The scores are based on crowdsourced Opensignal data, meaning they reflect where and how people actually used their phones during the survey period (August 2025 to July 2026). A network with a lower overall score can still perform well in the specific locations where individuals use it most.