AT&T announced in October of 2011 that they would begin throttling data usage for users still on an Unlimited Data Plan. Original iPhone users are the only one who have kept their unlimited plans, while newer customers on AT&T have been stuck using tiered data plans, which were just restructured last month.

In October’s announcement, AT&T said they will only throttle the top 5% of data users. AT&T warns users that they will be throttled when they fall under that tier, usually passing more than 10GB of data for the month. However, things didn’t seem to go that way for blogger John Cozen who only used 2GB of data before getting the notification. Cozen reached out to AT&T upset, who then responded..

To give you a baseline – the average data use across the country by the top 5% of AT&T smartphone customers was 2GB per month, effective August 2011. The amount of data usage of our top 5% of heaviest users varies from month-to-month and by market, based on the usage of others and the ever-increasing demand for mobile broadband services. To rank among the top 5%, you must use an extraordinary amount of data in a single billing period. It’s not how much time you spend using your device, it’s what you do with it….You’ll see the biggest impact when you try to stream video or upload large files. Speeds will be reduced considerably with those types of data transactions, though you should still be able to check e-mail and browse the Web. 

Cozen was obviously angry paying $30 a month for unlimited data — priced the same as the 3GB plan AT&T currently offers — and being throttled only after 2GB. AT&T confirmed with Cozen that the throttling wasn’t a mistake, and that 2.1GB falls in the top 5%. AT&T tried to convince moving Cozen to one of their new plans.

Currently, AT&T offers customers 300MB for $20, 3GB for $30, and 5GB with tethering for $50.

As MacRumors points out, the throttling seems to be specific to different regions, as some users still on unlimited who use more than 2GB have yet to been throttled.

Are you still using AT&T’s original truly unlimited $30 a month plan that was offered for the first iPhone? Is your data being throttled?