Three is launching an app that will allow customers to call and text even when they are only connected by WiFi.

One of the reasons Three is introducing the app, known as Three inTouch, is to ensure people can still make calls in buildings that can’t be penetrated by mobile networks, and in rural areas that don't receive a mobile signal. 

Three inTouch is due to be rolled from early August, meaning that Three's customers will be among the first in the UK to benefit from the new technology. It will be available for free to all Three’s contract, SIM and Pay As You Go customers.

Rival EE also announced on Friday that it will be rolling out voice over Wi-Fi (VoWi-Fi) to its customers. However, EE, the UK’s leading mobile operator according to mobile performance analysts Rootmetrics, is building the technology into the native dialler, which means users don’t have to open an app beforehand.

EE said VoWi-Fi will be available to its customers this autumn.