Sorry, I am new to the forum and tried searching this but didn't find the exact answer I was looking for... When using facetime on the Iphone 4, does it use GB usage?...if so, how much? And if you are on Wifi, is the usage unlimited since you are using the Wifi? I want to be able to use it, but I want to make sure I'm not going use up all of my GB's with this feature. If someone could help that'd be awesome..thanks!