FCC Chairman Tom Wheeler isn't happy about Verizon's plan to start slowing down customers on unlimited data plans this October. In fact, he seems really angry about it. Verizon announced the update to its "network optimization" policy on Friday, making sure to note that throttling will only happen under very specific circumstances — and only when network cell sites are experiencing heavy demand. But those assurances do nothing for Wheeler, who says he's "deeply troubled" by the news.

His tone gets even harsher as the letter goes on. "It is disturbing to me that Verizon Wireless would base its network management on distinctions among its customers' data plans, rather than on network architecture or technology." Verizon and other carriers that have implemented throttling say they have every right to do so since it falls under "reasonable network management." But Wheeler is also critical of this defense. "I know of no past Commission statement that would treat as reasonable network management a decision to slow traffic to a user who has paid, after all, for unlimited service."

Wheeler floats another interesting point in his letter to Verizon Wireless CEO Dan Mead: throttling LTE data may violate the obligations Verizon undertook when it acquired valuable C Block spectrum. Those rules specifically state the largest US carrier "may not deny, limit, or restrict the ability of end users to download and utilize applications of their choosing on the C Block networks." Wheeler has asked Mead to offer his thoughts on the subject in a "prompt" response. He's also interested in hearing Verizon's "rationale for treating customers differently based on the type of data plan to which they subscribe," and why throttling and similar measures are necessary for such a vast LTE network to begin with.

Again, throttling is common across every other major US carrier, so it's a bit odd to see the FCC come out swinging so aggressively at Verizon. Wheeler seems to be hinting that those C Block rules make a difference here, though the FCC's attempts to go toe-to-toe with Verizon have sometimes backfired in disastrous ways. We've reached out to Verizon for comment.