Three has confirmed it will begin rolling out Voice over LTE (VoLTE) technology to customers this autumn, with the aim of improving call reliability across its network.
The strategy hinges on Three adding 800MHz spectrum to its current 1800MHZ spectrum, which means that calls as well as data will be handled using 4G.
In turn, this should make it much easier to hold conversations in places where coverage had been patchy.
In particular, those who use their phones indoors are likely to see a major uplift in the service.
The company, currently in talks to buy O2, forecasts that one million customers will benefit by the end of 2015, with a further 7.5 million using VoLTE towards the end of 2016.
However, users will need the latest high-end smartphones in order for VoLTE to work.
The Samsung Galaxy S6 and iPhone 6 have the tech baked in, with all top of the range devices set to come with it in the near future.
Three has also said that its InTouch Wi–Fi calling service will soon no longer require a dedicated app and will instead switch seamlessly between cellular data and wireless networks.