Updated

AT&T says it's placing a limit on the amount of data its home Internet subscribers can transfer in a month, in an attempt to curb "data hogs."

AT&T says it will start charging extra after subscribers go past 150 gigabytes in a month, an amount it says only 2 percent of subscribers reach. In practice, only frequent movie downloads or perhaps constant videoconferencing can propel subscribers close to the limit.

Beyond the limit, AT&T will charge $10 per 50 gigabytes.

Most U.S. Internet service providers already place limits on data traffic, and AT&T Inc. has itself experimented with lower caps. However, low usage caps turned out to be very unpopular when

Time Warner Cable Inc. tried to institute them, and ISPs have moved away from the idea.