secure your voice minutes
FaceTimeis a built-iniOSandmacOSapp that runs on Apple devices.
This was not possible in previous versions, which allowed only video calls.
Why Voice and Not Video?

Apple, Inc.
But there are moments in which you might prefer to make a simple voice call.
The primary reason isdata consumption.
Another reason: We simply don’t always want to be seen.
Any version prior to iOS 7 does not support voice calling on FaceTime.
In fact, you could launch a call right from your unit’s contact list.
Turn the app on by touching theon/off switchand then selectUse your Apple Account for FaceTime.
Enter yourApple Account and password.
Your phone number will automatically be detected.
Complete the registration and confirm.
In some versions of iOS, this option is called “Apple ID.”
Then, just click theAudiobutton to make an audio-only call.
During a call, you’re free to switch to and from video calling.
Video calling, of course, will be subject to your approval and to that of your correspondent.
you’re free to end the call by pressing theEndbutton at the bottom, as usual.