AT&T has begun sending warnings to its top data users, reports 9to5Mac, telling the users that they’re in the top 5% of data users, and to start using WiFi to avoid speed reductions.
![AT&T iPhone Throttling](http://www.mactrast.com/wp-content/uploads/2011/09/ATT-iPhone-Throttling.jpeg)
The changes will begin coming into effect tomorrow for holders of unlimited data plans, and those who are in the top 5% of data users are subject to reduced speeds from AT&T. The customers can still use unlimited data while their speed is reduced, and their speeds will be restored to normal at the beginning of their next billing cycle.
AT&T will warn affected users by providing several notices and a grace period before limiting their speed. I can’t help but question however: at what point does “unlimited” data cease to be unlimited?