You can take calls—and make them—right from your iMac. You can also receive and send text messages.
Note: Internet and Wi-Fi connections are required in order to make or receive phone calls on your iMac.
Take or make a call. When someone calls your iPhone, click the notification that appears on your iMac screen and your iMac becomes a speakerphone. If you want to make a call, click a phone number in a Spotlight search or in an app such as FaceTime, Contacts, Safari, or Calendar. You need a nearby device (iPhone or iPad) with a cellular connection in order to make phone calls.
Learn more. See Set up iPhone to get SMS texts on Mac in the Messages User Guide.