Updated at 7 p.m. PT to indicate customers will have a tool to measure their usage.
In an effort to keep "bandwidth hogs" in check, AT&T is testing the idea of placing limits on how much Internet data its subscribers can transfer each month.
The test, which began being applied in the Reno, Nev., area on Saturday, limits customers of AT&T's slowest DSL service to 20 gigabytes of monthly data transfers, while users of the fastest service will be limited to 150 gigabytes. Customers will have access to an online tool to track their usage and will receive notification when they reach 80 percent. Those who exceed their limits will be charged $1 per gigabyte.
Existing subscribers will be assigned the 150GB limit regardless of their subscription level. The limits will apply only to new subscribers in the Reno area.
The caps are intended to discourage heavy users, such as virtual reality gamers and file swappers, from causing network congestion. AT&T estimates that just 5 percent of its subscribers use up to 50 percent of the network's capacity.
Regular Web and e-mail use shouldn't come anywhere close to the limits, but regular users of streaming services such has Netflix could test that limit. A standard length movie downloaded over the Internet requires about 2 gigabytes.
The test follows new plans introduced last month by Comcast, the nation's second-largest Internet service provider, in which subscribers would get a 250 gigabyte limit. Users who exceed that limit would reportedly face fines or possible suspension of their account.
Time Warner Cable and FairPoint Communications are also reportedly exploring instituting traffic limits.