Make a FaceTime audio call from Messages
You can start a FaceTime audio call in Messages.
Send a message to the person you want to have an audio call with.
Click Details, then click the Audio button .
If you don’t see the Audio button, you may need to sign in to FaceTime. You can choose which audio input device to use in Sound preferences.
To start a FaceTime call using a different email address or phone number listed in your friend’s contact card, click and hold the Audio button .
For more information about using FaceTime to make and answer audio calls, see Make video and audio calls.