Call relay, part of Apple's Continuity features, lets you answer and place calls from your iPhone using your Mac, without having to scramble to find your phone. So if it's somewhere else charging, or if you forgot it in your jacket or backpack, as long as you've got your Mac handy, it's no problem! You do have to be logged into the same Apple ID (iCloud account) and on the same Wi-Fi network. Because call relay uses the same phone number, carrier, and plan as your iPhone, the person on the other end can't tell the difference. It also shows you the caller's number, contact picture, and more, so you don't lose out on any features. Best of all, it's really easy to use!