In a letter sent to the U.S. House Committee on Energy and Commerce Wednesday, Free Press asked Congress to conduct a "broader inquiry" into the practice of capping Internet users' bandwidth usage at a certain level and charging them overage fees for exceeding their caps.

Free Press contends that the overage fees that some ISPs have been charging for exceeding monthly bandwidth caps seem "well above the marginal cost of providing Internet service," as the group notes that overage charges for some wireless services can range anywhere from US$50 to $480 per GB. For instance, according to AT&T's Web page detailing available data rate plans, users who pay $60 for their DataConnect services get a monthly 5GB bandwidth cap and are to pay $0.00048 per additional kilobyte of data they consume, or about $480 per every gigabyte over the cap. Thus, a user who consumed three times the amount of data allowed by the company's bandwidth cap would be charged about $4,800 extra per month.

Free Press concludes its letter by urging Congress to formally investigate the ISPs' pricing schemes for capped services and to "consider whether above-cost metered pricing for broadband constitutes an unfair business practice." The group also calls upon the ISPs to fully disclose information about the marginal costs to carriers when users exceed their cap limits.

Trials for capped Internet services have proven controversial for ISPs. Time Warner Cable, for instance, recently its trials of capped services in the wake of customer backlash and negative publicity from consumer groups. ISPs have been experimenting with implementing bandwidth caps since last year, when Comcast, Time Warner Cable and AT&T announced they were trialing new capped services.