Three is the first network in the UK to enable VoLTE (voice over LTE), throwing the switch to make it possible to make calls and send messages over the 4G network.
Moving voice and messages to 4G means that Three can offer better performance in some low-reception areas, as well as a better connection indoors. Because Three is using its new 800MHz spectrum for 4G Super Voice, penetration in hard to reach places should be better.
VoLTE is something that all the UK networks are in the process of enabling, but Three is the first to set the service live for its customers. We've recently heard EE and Vodafone say that it should be coming soon to those networks too.
That will mean that your device can stick to 4G all the time. In the current arrangement, you'll be using data on the 4G network, but have to switch back to 3G or 2G when you want to make a call - this can cause a slight delay as you switch over.
Three says that its 4G Super Voice covers 50 per cent of the UK population indoors, expanding to 65 per cent by the end of the year.
"By the end of the year, one million of our customers will have access to better indoor coverage and be able to use their phones in more places than ever before. We are proud to be the first network to roll this out across the country," said Bryn Jones, chief technology officer at Three.
Three says that the service will be available on the Samsung Galaxy S5 from launch, but you'll need a software update to enable the service on other devices. These updates will be rolled-out when ready for handsets. Three has also confirmed that it will work on the new iPhone.
What's missing from the news is any sign of Wi-Fi Calling. Wi-Fi Calling and VoLTE are stablemates, allowing hand-off of calls over LTE to calls over Wi-Fi without dropping a connection. Although Three is the first network to announce VoLTE, it's yet to announce Wi-Fi Calling.