It would appear that some owners of Apple devices are having issues with FaceTime, the problems appear to be affecting iPhone and iPad users running Apple iOS 6.
According to MacRumors there have been multiple reports of iOS 6 users having issues with FaceTime, with owners of the iPad and iPhone with iOS 6 installed unable to make and receive FaceTime calls.
The issues with FaceTime do not appear to be affecting all versions of iOS 6, some users running iOS 6.1.6 appear to be able to make and send FaceTime calls, and some devices with iOS 6.0.1 are reporting not being able to use the service.
There have been various reports of these issues over at the Apple forums, and some users have even reported problems with FaceTime on OS X 10.8 Mountain Lion.
The official response from Apple so far appears to be to update to iOS 7, although the issue may be temporary so you may not need to update to iOS 7 if you don’t want to.
If you have having problems with FaceTime on iOS 6, leave a comment and let us know, also let us know which version of iOS 6 you are running.