Everything Everywhere (EE) has announced live trials of placing voice calls over a WiFi connection as part of a £275 million investment. If successful, the service will allow subscribers to use their phones for voice calling over a WiFi connection in areas where previously there would not have been any coverage.
Your phone will need to support the feature, however, which EE plans to roll out in the Autumn. Whilst 4G technology provides better coverage in rural areas, it is not currently possible to make a voice call over a 4G connection: your phone actually falls back to 3G or 2G to make a voice call even in an area with 4G coverage.
EE plans to roll out Voice over LTE (VoLTE), the service that does allow for voice calling over a 4G connection, in 2015.