To contact a person using Facetime on your Mac computer, open Facetime and select the person's contact information from the address book. The person you are calling is notified and has the option to accept or decline your call.
A FaceTime call can be made from your Mac computer to another Mac computer, iPod Touch, iPad, or iPhone. To make a call to an iPhone, use the phone number of the person you are trying to reach. To make a call to another computer, iPad, or iPod Touch, use the email address of the person you are trying to reach.