Some reasons why FaceTime fails to work include outdated iOS software on an Apple device, incorrect date and time settings, lack of an Internet connection, incorrect contact information or FaceTime being turned off. Other causes may include incorrect FaceTime login credentials, a blocked contact or the FaceTime application being uninstalled.
A possible solution to the problem of FaceTime not working is to update both devices that are attempting to connect with one another. If the problem with FaceTime started on Apr. 16, 2014, both devices may have a device certificate that is expired. In certain devices, FaceTime may also not be turned on by default. A user can go into his Apple device settings and turn the application on under the "Restrictions" tab. Both users attempting to use FaceTime must also be connected to either a working Wi-Fi network or be subscribed to a data plan.
The FaceTime application was released on iOS devices on June 24, 2010, and requires at least iOS 4 to operate. FaceTime allows users on any Apple device to connect with one another through a video or voice call. As of 2014, the application is not compatible with non-Apple devices or other applications supporting video calling services.