Notice Netflix isn't as pretty on your smartphone as on your TV? Don't blame your wireless carrier. Netflix says it caps its video streams at 600 kilobits per second—meaning videos are shown at a lower quality—on many carrier networks, including AT&T and Verizon, to prevent customers from blowing past their mobile data caps.

(The idea being customers hit with a massive phone bill might then stop Netflix viewing on the phone.) Indeed, streaming two hours of HD Netflix video would use up a month's worth of data allowed on an $80 Verizon plan, reports the Wall Street Journal.

Netflix has actually been doing so for five years but only fessed up after T-Mobile CEO John Legere last week said AT&T and Verizon were throttling their customers' video; they denied it, and Netflix came forward.

But it adds it doesn't throttle T-Mobile and Sprint customers. Netflix says that's because they typically face slower network connections, rather than overcharge fees, once they've hit their data limit.

But Gizmodo notes this "complicates Netflix's stance as a net neutrality advocate" and "skirts dangerously close to breaking the principle of treating all packets the same." "We're outraged to learn that Netflix is apparently throttling video for their AT&T customers without their knowledge or consent," says a rep for AT&T, which has millions of customers with unlimited data plans, per CNET.

To ease concerns, Netflix says it will release a mobile "data saver" feature in May that will enable users to "stream more video under a smaller data plan, or increase their video quality if they have a higher data plan."

This article originally appeared on Newser: Netflix Has Kept a Mobile Video Secret for 5 Years

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