Last week, both AT&T and Verizon came under fire by T-Mobile CEO John Legere. He thought both were throttling Netflix traffic for their subscribers, but it turns out Netflix was restricting the flow of data.

Netflix said it caps streams at 600 kilobits-per-second for AT&T and Verizon customers, delivering less than half the speed of T-Mobile and Sprint users. The reason for the decision, according to Netflix, is a built-in protection against data caps that could consume an entire $80 a month Verizon data plan (10GB) in two hours time if streamed in HD.

As for why it doesn’t limit T-Mobile and Sprint users, “historically those two companies have had more consumer-friendly policies,” a Netflix representative said.

That said, it should be noted that T-Mobile streams Netflix at a lower quality (480p) for its Binge-On users and Sprint used to throttle all of its video traffic, but stopped the practice last year. T-Mobile users without Binge-On have their speeds throttled only after they pass their bandwidth allowances.

For Verizon and AT&T, however, this throttling happens automatically.

Netflix has been an outspoken supporter of net neutrality, a concept that should see all web traffic being created equally. Net neutrality rules, however, only apply to ISPs, so Netflix can throttle traffic as it sees fit without violating Title II guidelines.

Of course, working with AT&T and Verizon to come up with a fix might have been a better solution than throttling in secret; neither company knew that its traffic was being slowed.

“We’re outraged to learn that Netflix is apparently throttling video for their AT&T customers without their knowledge or consent,” said Jim Cicconi, AT&T’s senior executive vice president of external and legislative affairs.

Moving forward, Netflix says it’s exploring “new ways to give members more control in choosing video quality” and that it’s working on a “mobile data server’ that would be rolled out this year to preserve bandwidth.

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