Start a FaceTime call from an URL
I love FaceTime. The sound is crystal clear, which is important for me who learnt English as a Second Language. While I’m sure you’re well aware of how to start a FaceTime call (if not, Apple has a great video), you may not know that you can also use links.
facetime:// will start a FaceTime video call
facetime-audio:// will start a FaceTime audio call
You can use this in many places. I use it in my mail signature, to give an easy way for recipients to call me. You can use your phone number of your Apple ID. Note: you can use tel:// for standard phone calls.
Reference: FaceTime Links