As far as I know, FaceTime audio only allows you to call other FaceTime users, not old-fashioned landlines, mobile phones etc. Google Voice is nothing new thou

As far as I know, FaceTime audio only allows you to call other FaceTime users, not old-fashioned landlines, mobile phones etc. Google Voice is nothing new though. Google voice already offered VOIP (I regularly use an app called "Talkatone" for this). What's changed is that Google now offers a nicely packaged, official app for this.