Here's How:
- Begin by ensuring that FaceTime is turned on for your iPhone 4. Do this by tapping the Settings app on your home screen. Scroll down to Phone (or, in some versions of the iOS, FaceTime) and tap it. Move the FaceTime slider to On.
- FaceTime calls can only be made when the iPhone is connected to a Wi-Fi network (AT&T and Verizon currently block FaceTime calls over their 3G cellular networks). Connect your iPhone to a Wi-Fi network.
- FaceTime calls can also only be made to other iPhone 4s, 4th gen. iPod touches, iPad 2s, or Macs that have FaceTime activated and are connected to Wi-Fi networks (or, in the case of Macs, Ethernet networks). If the FaceTime icon has a question mark on it when you place your call, it may be because the person you're calling can't accept a FaceTime call for one of those reasons.
Once those requirements are met, there are two ways to FaceTime someone. First, you can simply call them as your normally would and tap the FaceTime icon when it lights up after the call connects.
Alternatively, you can browse through your iPhone address book, find the person, tap on them, and tap the FaceTime button on their page in your address book.
Your FaceTime call will begin just like a regular call, except that your camera will turn on and you'll see yourself. The person you're placing the call to will have the chance to accept or deny your call by tapping an onscreen button (you'll have this same option if someone FaceTimes you).
If they accept it, FaceTime will send video from your camera to them and vice versa. Both a shot of your and the person you're talking to will be on screen at the same time.
- End a FaceTime call by tapping the End button on the bottom of the screen.

