From the home screen, scroll to and tap the Extras folder.
Note: iPhone 4 only supports Facetime over a Wi-Fi connection. FaceTime calls are supported once signed into FaceTime using an Apple ID.
FaceTime is supported on the following devices and systems:
Tap the preferred contact.
To start a video call directly, tap the preferred FaceTime icon.
Wait while the call is connected.
To end the call, tap End.
The call is now complete.