AT&T eases up on throttling of grandfathered unlimited data plans for smartphones

The change, spotted by Ars Technica, undoes a controversial tactic in which AT&T would throttle unlimited plan users exceeding 3 gigabytes of 3G data per month, or 5 gigabytes of LTE data, regardless of network conditions. A U.S. Federal Trade Commission lawsuit is ongoing, and although AT&T has denied any wrongdoing, it recently promised it would make improvements to throttling policies.

The new language on the AT&T website states that people may be throttled if they exceed the 3- and 5-gigabyte thresholds, but only "at times and in areas that are experiencing network congestion."

The carrier's throttled speeds can be less than 0.5 megabits per second. That may make many smartphone uses difficult or completely impractical, particularly streaming music and video.

AT&T's approach is now in line with T-Mobile, Sprint, and Verizon, all of which use congestion-based throttling. The carriers may soon have little choice, as Federal Communications Commission rules limiting throttling to "reasonable network management" are due to take effect next month.