It appears that the AT&T unlimited data is really not unlimited, because AT&T continues to throttle the top 5% of data hogs. The amount of data that equals the top 5% of changes monthly, therefore some new people may be notified each month.
The throttling stops at the end of the billing period and users then get the fast speeds they previously encountered.
In July, 2011, AT&T updated its policy for data hogs that started October 1, 2011. Some believe that the effort is make the heavy data users change plans for its new higher priced plans that have higher monthly rates but lower prices per gigabyte.
"Smartphone customers with unlimited data plans may experience reduced speeds once their usage puts them in the top 5% of our heaviest data users. We will continue to send reminders and communicate with these customers ahead of time as their usage approaches the top 5%. For 95% of our smartphone customers this continues to present no impact." AT&T Seth Bloom stated to Phone Scoop in an email.
AT&T's original statement reported "But even as we pursue this additional measure, it will not solve our spectrum shortage and network capacity issues. Nothing short of completing the T-Mobile merger will provide additional spectrum capacity to address these near term challenges.|"