If you see Add Wi-Fi Calling For Other Devices: Turn it on.
This option allows calls using your other Apple devices that are on the same Wi-Fi network as your iPhone.
If you turn on Wi-Fi Calling on your iPhone, you might be asked to turn on Calls from iPhone on your Mac when you open FaceTime on your Mac. If you don’t get this notification, do the following.
In the FaceTime app Change RTT settings for accessibility on Mac