T-Mobile said Thursday that it would do away with tiered data plans and offer unlimited data to new customers starting in September. However, the plan comes with some exceptions that have, once again, called into question the mobile carrier’s commitment to net neutrality.

The new plan, dubbed T-Mobile One, will no longer cap the use of 4G LTE data based on a monthly allotment. However, subscribers who use more than 26GB of mobile data a month—about 3 percent of customers, according to T-Mobile—may be subject to having their usage throttled to slower speeds.

What has more clearly drawn the attention of net neutrality activists, though, is how T-Mobile will treat streaming video on its network. Subscribers to the T-Mobile One plan will have videos limited to streaming in standard definition, or 480p quality.

In order to view videos in high definition on the carrier’s network, customers will have to pay $25 per month on each line that would like to view videos at higher qualities.

Electronic Frontier Foundation (EFF) senior staff technologist Jeremy Gillula told the Daily Dot the organization is still gathering information regarding T-Mobile’s unlimited data plan. But he noted, “From what we’ve read thus far it seems like T-Mobile’s new plan to charge its customers extra to not throttle video runs directly afoul of the principle of net neutrality.”

Gillula also said the decision to limit video streaming quality may also violate the Federal Communications Commission’s (FCC) Open Internet Order, which he explained “explicitly said that ISPs can’t throttle traffic based on its type, or charge customers more in order to avoid discriminatory throttling.”

The Open Internet rules from the FCC specifically prohibit companies from blocking, throttling, and engaging in paid prioritization.

“A person engaged in the provision of broadband internet access service, insofar as such person is so engaged, shall not impair or degrade lawful internet traffic on the basis of internet content, application, or service, or use of a non-harmful device, subject to reasonable network management,” the rules read.

The 480p cap on video streaming is a carryover of T-Mobile’s Binge On plan that was announced last year. Part of its ongoing “Un-carrier” branding, Binge On allowed users to watch video content from select video streaming apps like Netflix, Hulu, and YouTube without it counting against their monthly data allotment. However, the video quality was limited to standard definition.

At the time, the plan was questioned by net neutrality advocates. The practice of exempting particular services from metered data usage, known as zero rating, is viewed as providing an unfair advantage to those services by incentivizing customers to use them.

The company was similarly questioned in 2014 when it announced its Music Freedom plan that zero rated streaming music apps. Despite T-Mobile’s effort to add as many apps as possible to the plan, it was still viewed warily by many concerned with net neutrality rules.

Earlier this year, EFF researchers tested T-Mobile’s network to see how it handled video and found the carrier to be throttling the connections of customers when they streamed or downloaded videos. While T-Mobile claimed to be “optimizing” the stream at 480p, the EFF suggested it was instead limiting mobile bandwidth to 1.5Mbps while viewing video content—far slower than the average LTE connection.

T-Mobile CEO John Legere responded to the EFF by denying the charges and asking, “Who the fuck are you, anyway, EFF? Why are you stirring up so much trouble, and who pays you?” Legere later clarified that he knew what the EFF is, and “I’m sure they do a lot of great things for a lot of consumers, but innovation can be controversial!”

A spokesperson for the FCC told the Daily Dot that “the Commission’s informal policy review is ongoing. Chairman Wheeler said the Commission would keep an eye on new developments in this area and we are continuing to do so.”

T-Mobile did not respond to a request for comment on the EFF’s statement when contacted by the Daily Dot.