When Steve Jobs showed off FaceTime — its iPhone 4 video chat feature — at Apple’s Worldwide Developers Conference, it wasn’t exactly clear how it affected your cellular minutes. Since FaceTime video calls can be initiated right from a standard voice call, some speculated that it would continue to use up your cellular minutes — despite video calls being limited only to Wi-Fi.

Now with only a few days to go before iPhone 4 launches, an Apple representative has cleared up the matter: “The voice call ends as soon as the FaceTime call connects. The FaceTime call is over Wi-Fi so does not use carrier minutes,” the rep tells Business Insider.

When FaceTime finally works over 3G networks, it will be interesting to see if Apple maintains this policy. At that point though, FaceTime calls will also be eating up cellular data bandwidth — something which new AT&T customers will have to keep track of now that the carrier has ended its unlimited data plan.

Counting mobile minutes for 3G FaceTime calls for users with metered data plans would seem like overkill, and it’s not the sort of thing that would win AT&T any more fans.