Parts of Wales and the South West of England have been identified as the most problematic areas for mobile connectivity in the UK. Despite the advancements in technology, many individuals still face issues with unreliable or nonexistent mobile signals.
Major mobile providers like EE, O2, Three, and Vodafone claim to cover approximately 99% of the UK with their 4G networks. However, a recent study conducted by consumer group Which? and data company Opensignal indicates that the quality of service can vary significantly depending on the specific location.
Utilizing real-world data from consumer mobile devices, a network quality map has been created to assess the consistency of signals in different postcode areas up to August 2025.
In Tenby’s SA70 area in Wales, a popular coastal town, mobile users are reported to experience a reliable connection only 54.3% of the time. The quality of service ranged from 71% for EE customers to as low as 38% for Three customers.
Similarly, in Llandrindod Wells’ LD1 area, the network quality was rated as the second-worst, with an overall score of 54.8%. Customers of Three encountered a good connection only 41% of the time, while O2 users enjoyed a 66% rating.
In England, postcodes TA5 in Taunton, Somerset, and TR4 in Truro, Cornwall, were identified as having subpar network quality scores of 56% and 57.8%, respectively. O2 was noted as the least consistent network in both regions, with EE providing the most reliable connection.
The study highlighted that individuals in larger cities such as London, Nottingham, and Glasgow tend to have better mobile coverage. Postcodes SE11 in London and NG3 in Nottingham were identified as having the best quality mobile coverage, scoring 87.8%.
Natalie Hitchins, the head of home products and services at Which?, emphasized the significant disparities in mobile coverage across the UK. Selecting the right mobile provider can make a substantial difference in experiencing seamless coverage or struggling to make calls from one’s residence.
The Which? mobile quality map, based on over 17 million network tests conducted across the UK in the past year using Opensignal apps, is a valuable resource for consumers seeking information on mobile network performance. The data is aligned with the Ofcom Map Your Mobile tool.
Top 5 postcodes with average network scores and the Bottom 5 postcodes were also outlined in the study, shedding light on the varying quality of mobile network services in different regions.