Company spokesman Michael Coe explained to the Associated Press that the top 5 percent of AT&T's DSL customers consume 46% of its total bandwidth, and overall usage is doubling every year and a half.
"A form of usage-based pricing for those customers who have abnormally high usage patterns is inevitable," Coe said, adding that AT&T has not yet decided on any specific plans or fees for its subscription packages.
While relatively common overseas, capped internet subscription programs have been rather scarce in the United States, and are likely to concern some gamers.
An HD movie downloaded from Microsoft's online Xbox Live Marketplace typically weighs in at 4.5GB, and demos of upcoming games can be in excess of a full gigabyte in size. Select PC games available on Valve's digital distribution platform Steam exceed 4GB.
Earlier this month, Time Warner announced that it was field-testing a new service plan in which subscribers would be charged $1 per every gigabyte of data downloaded over a 15- or 40-gigabyte cap, depending on subscription level.
Comcast is said to be considering a similar plan with a $15 charge for every 10GB downloaded beyond a 250GB limit.