Stephenson appeared before Kohl and Klobuchar during a hearing this month where he defended the merger. Klobuchar and Kohl grilled him on competition and potential consumer harms.
AT&T has said the allegations of phantom data charges are "without merit." An AT&T spokesperson told Ars Technica: "Unfortunately, there have been some incorrect claims about our data usage billing practices. We properly charge for all data that our customers send and receive, including data activity that runs in the background on smartphones and other powerful data devices."
The senators pointed out that customers have no way of verifying whether AT&T is telling the truth.
"We understand that AT&T contends these allegations of overcharging are untrue and that there is simply a misunderstanding as to how AT&T measures data and communicates that information in monthly bills. Yet, as you know, consumers cannot easily verify that the amount of data used in any given month is equal to what they have been charged for on their bill," their letter said.
An AT&T spokesman sent this comment: "We have received the Senators’ letter and look forward to providing them with information on how we bill for wireless data usage and specifically how our billing systems work. We are confident that our billing systems are accurate. We properly bill for all data that our customers send and receive, including emailing, downloading applications, browsing the web, downloading a video or streaming music. Other data activity includes real-time updates to applications, such as weather, sports scores, or stock tickers. Smartphones, tablets and other advanced mobile devices feature applications that often constantly run in the background and are engaged with our network. Customers always have the ability to monitor their own usage by going to www.att.com/dataplans or by dialing *DATA# from their AT&T wireless device.”