T-Mobile USA CEO John Legere apologized to the Electronic Frontier Foundation (EFF) for mocking its concerns about the wireless carrier's "Binge On" program that throttles online video.

In an "Open Letter to Consumers About Binge On," Legere said T-Mobile plans to meet with the EFF, which argues that T-Mobile is violating net neutrality rules. Legere was less gracious to the EFF last week when he answered their concerns by saying "Who the fuck are you, anyway, EFF? Why are you stirring up so much trouble, and who pays you?"

In his open letter yesterday, Legere wrote:

Look, by now you know that I am a vocal, animated and sometimes foul-mouthed CEO. I don’t filter myself and you know that no one at T-Mobile filters me either (no, they don’t even try). That means I will sometimes incite a bit of a "social media riot," but I’m not going to apologize for that. I will however apologize for offending EFF and its supporters. Just because we don’t completely agree on all aspects of Binge On doesn’t mean I don’t see how they fight for consumers. We both agree that it is important to protect consumers' rights and to give consumers value.

Binge On detects video and reduces its bandwidth, making it use less data. Companies that partner with T-Mobile get their data zero-rated—meaning it doesn't count against customers' data caps—but all or nearly all video is limited to about 1.5Mbps by T-Mobile. Binge On is enabled by default, but consumers can disable it.

The Federal Communications Commission is expected to meet with T-Mobile this week to discuss whether Binge On's throttling and zero-rating violate the net neutrality rules. T-Mobile will argue that the program benefits customers by letting them watch more video without going over their data limits and that customers who want full-quality video can simply turn the feature off.

Legere reiterated the carrier's position in his open letter.

"We use our proprietary techniques to attempt to detect all video, determine its source, identify whether it should be FREE and finally adjust all streams for a smaller/handheld device," he wrote. "(Most video streams come in at incredibly high-resolution rates that are barely detectable by the human eye on small device screens and this is where the data in plans is wasted). The result is that the data in your bucket is stretched by delivering streamed video in DVD quality—480p or better (whether you have a 2GB, 6GB or 10GB plan etc.) so your data lasts longer."

Legere didn't mention in the open letter that Binge On is enabled by default even for customers who pay extra for unlimited smartphone data. T-Mobile's Unlimited data customers do face a limit on mobile hotspot usage, so they could benefit from data cap exemptions and lower data usage if they use the hotspot to stream video to other devices.

Thirty-eight services have signed up to get their data zero-rated, and another 50 are "interested in coming on board," Legere wrote.

As for why Binge On is enabled by default, Legere wrote, "We strive to default all of our customer benefits to “ON.” We don’t like to make customers dig around to find great new benefits."

When contacted by Ars, an EFF spokesperson said, "We are grateful for the apology and appreciate Mr. Legere recognizing our work in fighting for the consumers. We too hope to have a discussion with T-Mobile regarding net neutrality and Binge On."