Apple iMessaging is part of Apple iOS notification system for text messaging. It is used by many of Apple Applications including Apple FaceTime and others. Apple iMessage traffic cannot be blocked. The reason is that makes use of redundancy by using any of the following (in order), if availble: wifi, cellular data service, cellular call signalling channel. Even if the users cellular data service is turned-off, iMessage with still send the message using the cellular call signalling channel.

This SonicWALL signature identifies legitimate Apple iMessage traffic.