Proposals to introduce national roaming in the UK will fall some way short of completely eliminating blackspots, according to a blog post by OpenSignal, a company which monitors network coverage using crowdsourced data.

According to reports earlier this week, the UK government is considering national roaming as a way to boost coverage in rural areas, enabling customers of one operator to “roam” onto a rival network when outside of coverage.

However, the suggestion has led to questions about how operators’ infrastructure investments will be impacted, as well as the commercial model which will support in-country roaming.

OpenSignal said the average UK user has no signal for 15 per cent of the time, which would fall to 7 per cent if national roaming is in place – “a huge improvement, but in no way ‘an end to mobile blackspots’.”

It came to this conclusion by assessing its statistics for “time on no signal”, and a subset of this called “time on emergency calls only” – when a subscriber is within the coverage area of another operator’s network.

OpenSignal also highlighted some issues that need to be considered. Firstly, the geographic and demographic split of subscribers across networks is not the same, meaning that perceptions of network coverage may not accurately reflect performance.

For example, it said that Vodafone UK has a much higher “time on no network”, but this may reflect the fact it has a good reputation for rural coverage and therefore attracts more customers outside of major cities.

These subscribers, therefore, may not be better served by any other network.

Contrastingly, a network with a poor reputation for rural performance will find subscribers concentrated in urban areas, who may see less time without network coverage, because cities are generally better connected.

Secondly, as the results show, while national roaming will improve the situation for subscribers notably, there will still be coverage holes, and the incentive for addressing this may be reduced – because providing additional infrastructure will no longer be a differentiator for operators.

“With better coverage information becoming more easily available, national roaming might end up limiting expansions that the networks themselves would make in order to appeal to different segments of a better-informed market,” OpenSignal concluded.