FaceTime is the iPhone 4's video calling function.

The iPhone 4 features two cameras - one on the front for video calling and a more advanced one on the back for taking photos.

You can use both of these cameras for making FaceTime video calls.

Here we show you how to make a FaceTime call, switch to a FaceTime call and switch cameras during a FaceTime call.

How to make a new call with FaceTime

1. Select the Phone icon from the homescreen
2. Select a contact
3. Select the FaceTime icon from the contact's phonebook entry
4. When the person you're calling accepts the FaceTime invitation, the video call will start

How to switch from voice to FaceTime call

1. Make a voice call by selecting the voice call button from the contacts screen
2. When you're on the voice call, tap the FaceTime icon on the screen (it looks like a video camera)
3. The call will switch to a FaceTime call when the person on the other end accepts the FaceTime invitation

How to switch between the front and back camera on a FaceTime call

1. Make a call using the FaceTime functionality (Steps 1-4 above)
2. Tap the switch camera icon in the bottom right of the screen
3. The camera view will automatically switch to using the rear-mounted camera