FaceTime calls are a great way to see who you're talking to, but there may come a time when you'd rather not be seen. Maybe you're not dressed for company, or maybe you simply don't want anyone to see who's with you, or behold the state of the world around you. While, Apple hasn't (yet?) enabled audio-only FaceTime calls, you can easily start a regular old FaceTime call and then turn off the video.
That's it. A green bar across the top of the screen will let you know your FaceTime call is still active, but video will be disabled.
To start video again, simply tap the green bar to return to the FaceTime app.
If you need more help with using FaceTime on your iPhone, iPod touch, iPad, or Mac, check out the articles below, or head on over to the iMore forums.