EE just became the first UK carrier to support Smart Number technology. It allows you to use your iPhone's number to make calls or send texts with an iPad or an Apple Watch or even a Mac or an iPod. You need a "main" device - iPhone 6 or newer, it has to be an iPhone and it has to run iOS 11.3 or later. Then you can pair up to 5 other Apple devices such as an iPad, Apple Watch or even a MacBook - you will find the compatibility list below. Best of all, the service is free. Once paired, incoming calls to your main number can be received on any of your paired devices. And outgoing...
Source: https://www.gsmarena.com/ees_new_smart_number_technology_lets_you_use_an_apple_watch_or_ipad_to_receive_calls-news-31610.php
