The latest offering in EE's loyalty drive is targeted at customers and small business owners who lose signal in their homes or offices.
Wi-Fi calling is only available on a limited number of devices to begin with, starting with the Lumia 640, Samsung Galaxy S6 and S6 Edge on 10 April. It will roll out more widely on compatible devices by the summer.
The service will not be available to pay-as-you-go or SIM-only plans.
O2 and Three offer a similar service, but require users to download the respective Tu Go or InTouch apps to make calls over Wi-Fi. EE by contrast claims to offer a seamless service, using the device's usual dialler and contacts book to make calls and send texts.
EE CEO Olaf Swantree said: "Losing coverage at home is a major frustration, and WiFi Calling will make a real difference to millions of customers across the UK, from basement flats in London to the most rural homes in the country.
"Our customers want to be able to call and text no matter where they are, and they don’t want to have to think about which app they need to use or if their friends have a particular third-party service."
EE's new service comes after the brand launched EE Film Club, its digital follow-up scheme to Orange Wednesday. It has also started offering customers free, portable phone chargers in a bid to boost its customer service.