A multi-university study released this week concluded that Sprint has been throttling the bandwidth of customers using Skype, Microsoft’s popular internet-based video chat service.
The study was produced by researchers at the Northeastern University and the University of Massachusetts using Wehe, a phone app designed to monitor the behavior of mobile network providers when users access streaming services such as YouTube or Netflix.
The goal of the project is to detect instances in which network providers are giving differential treatment (i.e., varying throttling rates) to certain applications.
Nearly 630,000 tests have been conducted using Wehe since January. The app is available to both Android (4.4+) and iOS users, allowing most smartphone users to participate in the research.
In a summary of its findings Thursday, the Wehe researchers said they’d discovered a “significant number of instances of Sprint throttling Skype.”
While a vast majority of throttling cases involved Android devices, the researchers attributed this in part to dataset bias, disclosing that 84 percent of their tests involved Android devices. Even so, Android users appear to be affected at a “higher frequency” than users of iOS devices, they said.
The researchers noted that while the tests had produced “strong evidence of Skype throttling” on Sprint’s part, they were unable to reproduce the throttling themselves. “This is likely because it affects only certain subscription plans, but not the one that we purchased,” the researches said.
An analysis of the data by the Seattle Times revealed suspected throttling of Skype users by Sprint in 34 percent of 1,989 “full tests,” which require the user to test the network speeds twice in a row.
In a statement, a Sprint spokesperson said, “Sprint is not throttling Skype. Sprint does not single out Skype or any individual content provider in this way.” The company also attacked the methodology behind the study, saying the researchers did not “provide the data they used,” leaving it unclear “how they researched their conclusions.”
The institutional review board that approved the study prohibits the researchers from disclosing their users’ test data. (The study is funded in part by a grant from the National Science Foundation and Google’s Faculty Research Award.) Despite Sprint’s assertion that the researchers’ methods aren’t available for scrutiny, the methodology behind the peer-reviewed study has been disclosed in great detail.
When challenged over its assertion that the research is murky, Sprint stopped responding to Gizmodo’s questions.
Last December, the Federal Communications Commission’s Republican majority overturned Obama-era rules meant to protect internet users from net neutrality violations, including the throttling of mobile applications and services.
However, the Wehe researchers wrote that their tests had conclusively shown that mobile providers had violated net neutrality in the weeks and months before the rules were actually repealed on June 11.