Verizon has found itself in hot water with federal regulators over its plan to slow traffic for certain customers.
In a letter sent to Verizon CEO Dan Mead on Wednesday, Federal Communications Commission Chairman Tom Wheeler said he is "deeply troubled" by the cell phone carrier's announcement. He demanded more details about the plan and questioned whether it's legal.
"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," Wheeler wrote.
The stern letter comes as Wheeler is under fire from liberals for proposing net neutrality regulations that they view as too weak to prevent abuse.
Last week, Verizon announced that it will begin slowing down 4G LTE data speeds for customers with unlimited plans when they try to connect to congested cell towers.
"Our network optimization policy provides the best path to ensure a continued great wireless experience for all of our customers," Mike Haberman, Verizon's vice president for technology, said in a statement at the time.
The FCC allows cellular carriers and home Internet providers to engage in "reasonable network management." But Wheeler warned the Verizon CEO not to try to use that exception as a "loophole designed to enhance your revenue streams."