Originally Posted by
gfunkdave
Yeah, the feature was introduced on iOS 8. Your phone communicates via the local wifi network with other devices signed into the same Apple account on the local network. It's the same way I can make regular phone calls on my iPad - it goes over wifi to my phone.
Apple marketed it as "continuity".
https://www.apple.com/ios/whats-new/continuity/
I've been using it since last fall, to make or receive calls and messages across multiple devices using one mobile phone number.