For years, US consumers have expected that they can head online without worrying about how long they browse or how much they download, but those days may be coming to an end if various ISPs have their way. Several of the major broadband providers are now experimenting with bandwidth caps, in which users will start to face fees once their total traffic exceeds a specified amount. It's safe to assume that users won't be thrilled about the change, so AT&T has apparently decided that the safest way to test its new billing system is by rolling it out in a market where the competition has already instituted usage caps of its own.

Although most ISPs have offered (practically) unlimited usage of their broadband connections, they don't guarantee that all their users can start streaming movies at once. Instead, they have budgeted for average use, a tactic that's running into difficulties as more users are downloading or streaming said movies. After Comcast's flirtation with targeting P2P users did not go over well with the FCC, a number of ISPs have started considering charging their users for gobbling up too much bandwidth.

Comcast was one of the companies that announced limits on data transfers, although it set them at a fairly expansive 250GB. Time Warner Cable has been notably less generous, trialing limits as stringent as 5GB a month on its lowest tier of service. At the moment, however, that trial is targeted to one area: sorry, Beaumont, Texas! ISPs need some time to test the monitoring software, which needs to handle both the ISP's billing and their users' self-monitoring, and they want to see how customers react.

Time Warner's decision apparently seemed like a gift to AT&T. After having pioneered its own program in Reno, Nevada, Broadband Reports has found that AT&T is planning on rolling it out next in Beaumont, a town that is fast on its way to becoming an Internet sinkhole. AT&T's caps will fall somewhere between those of Comcast and Time Warner and will limit its lowest tier customers to 20GB a month in traffic.

AT&T has also run into trouble guaranteeing that its U-verse service has enough bandwidth to support streams of high-definition TV, so it's also using throttling to keep the bandwidth use down. All of this, however, comes at the same time the company apparently has to compete with its fellow ISPs by offering more bandwidth to its customers. At some point, these two trends will make it clear to consumers that the promised bandwidth will simply allow them to run up their bills faster. The key question will be whether those consumers can find any service that offers either unlimited usage or reasonable traffic limits should they decide to look elsewhere.