"UK MOBILE OPERATOR Three has beat rival EE to it with the launch of Voice over LTE (VoLTE), or 'Super-Voice' as the firm has decided to call it.
Three's Super-Voice service will boost mobile coverage indoors and in rural locations by using low-frequency 800MHz spectrum which is better at penetrating buildings and can travel greater distances, according to the operator.
Three claimed that its 800MHz network covers 50 percent of the population, including the majority of London, Edinburgh, Exeter and Birmingham. That figure is expected to jump to 65 percent by the end of the year as the firm extends to more towns and cities, including Cardiff, Manchester, Liverpool and Bristol.
This doesn't mean that much of the population will be able to use Super-Voice just yet, however, as a VoLTE-compatible phone is need to take advantage. Three told us that the Samsung Galaxy S5, LG
G4 and unspecified Xperia handsets will be the first to gain Super-Voice functionality at launch.
Three said that new handsets will be added to its Super-Voice line-up regularly, including the new iPhone 6S and iPhone 6S Plus. The operator also told us that last year's iPhone 6 and iPhone 6 Plus will receive support later in the year, and that more Android phones will be added within the next month.
Three said it expects that up to 5.5 million customers could have access to 4G Super-Voice by 2017, subject to device compatibility and take up.
Bryn Jones, chief technology officer at Three, added: "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."
Three has beat its rivals to the punch, but EE and Vodafone are unlikely to be far behind as both have previously confirmed that a launch this summer was on the cards. No exact dates have been mentioned.
EE and Vodafone have one up on Three when it comes to their respective WiFi calling apps, however, as Three's InTouch offering is unable to hand off between a mobile and WiFi connection."