The U.K.- based telco has been testing VoLTE at its Newbury lab since August 2014, but until now it has kept quiet about when it will go live. Vodafone's next step is to conduct customer trials ahead of its commercial launch.

In addition, Voda plans to offer WiFi calling from this summer as well, which will help customers living in remote locations or in places where indoor signal is poor.

Voda's rival - EE is also making progress: It too aims to launch VoLTE and WiFi calling this year as part of a £1.5 billion, two-year investment programme.

U.K. operators are slightly behind the curve when it comes to rolling out VoLTE.

The world's first VoLTE services went live in South Korea and the U.S. in August 2012. Since then, the technology has been rolled out in Denmark, Hong Kong, Japan, Romania and Singapore, according to the Global mobile Suppliers Association (GSA).

"Our WiFi calling service will ensure that our customers never miss a call. It is another important step towards our commitment to build the U.K.'s strongest converged network," said Jeroen Hoencamp, CEO of Vodafone UK, in a statement.

Meanwhile, there are trials taking place in multiple markets. 80 operators in 42 countries are investing in VoLTE, the GSA says.

Total Telecom