AT&T Customers Stunned by 'Unlimited Data' Limit Top data users find smartphones 'throttled' By Evann Gastaldo, Newser Staff Posted Feb 13, 2012 7:26 AM CST 10 comments Comments This undated screen grab provided by Mike Trang shows a warning message on the screen of Trang's iPhone that he received from AT&T advising he was in danger of having his data speeds throttled. (AP Photo/courtesy of Mike Trang) (Newser) – AT&T stopped offering unlimited data plans in 2010, but some of the customers who already had the plans are finding "unlimited" doesn't necessarily mean what they thought it meant. AT&T has started "throttling" the top 5% of data users, cutting their download speeds by up to 99% and making their phones basically useless for anything other than phone calls and text messages. One throttled user found his phone went from loading a web page in a second to taking nearly two minutes; it happened two weeks into his billing cycle, when he reached 2.3 gigabytes of data. He pays $30 for his unlimited plan, and a limited data plan—for the same price—offers more data than that: 3 gigabytes per month. When customers call AT&T to complain, representatives urge them toward the limited plans, the AP reports. An AT&T spokesperson says not everyone in the top 5% gets throttled, only users in places where the network is congested at that particular time. Even so, once AT&T throttles a phone, it remains throttled for the entire billing cycle—even in the middle of the night when there's most likely no congestion. Verizon, on the other hand, only slows down its top users when they are connected to a tower that is actually congested, and it slows the speed as little as it can. T-Mobile, meanwhile, clearly states that it begins throttling at 5 gigabytes, whereas AT&T users don't know when they might be in danger of throttling until they get a text-message warning, which the AP notes is often quickly followed by the super-slow service. Sprint doesn't use throttling at all. One AT&T customer points out that there is little action users can take, since AT&T is still technically providing unlimited data. "They just guaranteed the highway," he says. "They didn't guarantee the speed limit."