A study has exposed flaws in the way that carriers measure data usage. A research team from UCLA published a paper titled Can We Pay for What We Get in 3G Data Access?, which looks at data traffic over US carriers and others, revealing that some were charging for data that was never received. The issue, first reported on by Computer World, stems from the fact that the carriers monitor outgoing data from their servers; if you lose signal, you'll still be charged for the lost data. As an example, the team found that, when on watching a YouTube video on a train traveling through a tunnel, they were overcharged by 7.2 percent. The most extreme test found an overcharge of 450MB. With wireless data already at a premium, such mis-measurement could dramatically reduce the amount of data you're able to receive before hitting your cap.

In the same paper, the researchers detailed a method through which users could circumvent some carriers' data measurements entirely, effectively gaining unlimited free uploads. By using the port used for DNS queries, which on the exploited networks was unmonitored, the team was able to send 200MB of data without charge. Guan-Hua Tu, a co-author of the paper, told us that "carriers should not be blamed" for the extreme mis-measurements: the research group's intention was to highlight the "limitations of current mobile data accounting architecture," not point the finger at data providers. He declined to name the carriers involved as not to provoke any controversy.