What is Wifi calling?

Wifi calling means your phone makes and receives calls over your home internet connection instead of the mobile network, which helps indoors and in places where the mobile signal is weak. Most providers publish this clearly: 1pMobile, 2degrees, 3 Macau and 4ka all state that they support it. 50plus Mobiel is the exception and states that it does not. Worth checking the wording before you sign if you rely on calls in thick-walled homes or a basement office.