The UK's mobile blackspots could be a thing of the past, if Three's 4G Super Voice service lives up to its claim.
Three says the technology allows mobile signals to travel further into buildings and to reach more rural areas. The result should be better coverage all over the UK.
4G Super Voice is the UK's first 4G mobile voice service. Previously, 4G customers had to drop to the 3G network when making phone calls. 3G signals don't penetrate very far into buildings, which meant indoor coverage was often poor.
4G Super Voice lets customers make calls on the 4G network, meaning enhanced coverage and fewer dropped calls.
"Indoor coverage across the industry is always the hardest problem to solve, so all networks, whether it's 2G, 3G or 4G will always have coverage blackspots," said Bryn Jones, chief technology officer at Three.
"The way I always think of it is, if you're trying to get to sleep at night and there's a party at the end of the street, the sound you hear is the bass, which is the low frequency. You don't hear the singing, which is the high frequency."
4G Super Voice is possible thanks to the low-frequency 800MHz spectrum, which came to the Three network following the 4G auction in 2013. This has shorter wavelengths than Three's 1,800MHz spectrum, so it's better at penetrating walls, which results in better coverage in buildings.
4G Super Voice currently covers 50% of the UK population for indoor coverage and more than three quarters of Edinburgh, Exeter and Birmingham. Three hopes to cover 65% of the UK by the end of the year.
To use the service, you'll need a phone whose antenna can pick up the 800MHz spectrum. You'll also need to update your software; keep your eyes peeled for an alert that will let you know when it becomes available.