While AT&T battles with the Federal Trade Commission in court over the practice of data throttling subscribers that pay for unlimited data plans, the wireless provider has redefined when throttling will occur. Basically, any LTE subscriber that surpasses 5GB of data consumption in a given billing period will continue to be throttled, but only during periods of heavy data congestion. Prior to this change, all LTE subscribers that broke the 5GB barrier were throttled all the time until the end of the billing period.

As detailed by Arstechnica, an AT&T support page posted earlier today states "As a result of AT&T's network management process, customers on a 3G or 4G smartphone or on a 4G LTE smartphone with an unlimited data plan who have exceeded 3 gigabytes (3G/4G) or 5 gigabytes (4G LTE) of data in a billing period may experience reduced speeds when using data services at times and in areas that are experiencing network congestion. All such customers can still use unlimited data without incurring overage charges, and their speeds will be restored with the start of the next billing cycle."

Of course, AT&T doesn't outline when or how often a network becomes congested due to increased data usage by subscribers. It's possible the new policy may unfairly impact subscribers that live in heavily populated areas with thousands of subscribers competing for the same data network, despite large network capacity. On the flip side, anyone that lives in a particularly rural area with limited coverage may be competing for bandwidth on a much smaller data network, thus they could be throttled often as well.

When data speeds are throttled, AT&T customers often see their download speeds drop from around 20Mbps to roughly half a megabit per second. At that speed, it becomes very difficult to stream video smoothly or any other task that requires a solid data connection. Of course, this only applies to customers that have been grandfathered to a new LTE phone with an unlimited data plan. Any subscriber on pay-per-GB plan would simply pay for more data after exceeding their current plan.