Study Finds Mobile Coverage in Caerphilly Boosted by VodafoneThree Merger

Network analyst firm Streetwave has published the results from a recent survey they conducted into mobile network coverage and mobile broadband (4G, 5G) speed across Caerphilly in Wales, which involved two surveys over an 18-month period and revealed a strong post-merger boost for Vodafone and Three UK (VodafoneThree). On the flip side, O2 actually suffered a decline.

Streetwave typically works by harnessing waste (bin / refuse) collection trucks to map mobile network coverage and speeds across various parts of the UK (e.g. here, here, here, here and here). In this setup, refuse trucks are installed with several off-the-shelf Smartphones using special software, which run continuous network tests (once every 20 metres in rural areas and 5m in urban areas) as the vehicles go around their routes.

The data they collect is often then used by local authorities to help identify areas that may require additional intervention in order to improve local mobile coverage and or network capacity, while also giving locals access to some of this data via address-based coverage checkers and interactive maps (https://app.streetwave.co/coverage-checker).

In terms of their work in Caerphilly, which was supported by the local authority, Streetwave conducted two studies – the first survey took place in September 2024 and the second in March 2026. The Essential Coverage scores from EE, O2, Vodafone and Three UK were then compared – defined as locations where the mobile networks provide users with data speeds of above 1Mbps download, 0.5Mbps upload, and below 100ms (milliseconds) of latency (i.e. covering or allowing only the most basic of use cases / needs).

Overall EE and Vodafone were tied for the top spot, with 97% of the area for both having access to Essential Coverage. But Three UK saw the biggest increase (+21 percentage points) in its coverage to hit 90%, and they were followed by Vodafone (+17 points). Perhaps surprisingly, O2 recorded a sharp decline between the two studies (-12 points) and fell to 73%.

Essential Coverage Scores for Caerphilly

The study also provided data on the average mobile broadband download and upload speeds for each operator, which we’ve posted below.

Mobile Download Speeds in Caerphilly
(Previous 2024 Result in Brackets)

➤ Three UK – 26.49Mbps (up from 21.93Mbps)

➤ EE – 18.59Mbps (down from 26.28Mbps)

➤ Vodafone – 17.56Mbps (up from 16.85Mbps)

➤ O2 – 9.76Mbps (down from 11.17Mbps)

Mobile Upload Speeds in Caerphilly
(Previous 2024 Result in Brackets)

➤ EE – 9.29Mbps (up from 5.42Mbps)

➤ Vodafone – 7.64Mbps (up from 4.57Mbps)

➤ Three UK – 7.04Mbps (up from 4.28Mbps)

➤ O2 – 5.33Mbps (up from 4.24Mbps)

Both EE and O2 seemed to suffer a fall in download performance between the two studies, although outside of those the story was broadly one of improvement.