The Federal Communications Commission has sent a strongly worded letter to Verizon Wireless asking why the company has made it a policy to throttle customers with unlimited data plans.

The note, addressed to Verizon Wireless CEO Daniel Mead and authored by FCC chairman Tom Wheeler, takes the company to task for a recent announcement that users in the "top 5%" of data consumers would soon experience a slow down in data speed if they are on a busy network.

See also: Even Major League Baseball Wants Net Neutrality

"I am deeply troubled by your July 25, 2014 announcement that Verizon Wireless intends to slow down some customers' data speeds on your 4G LTE network starting in October 2014," Tom Wheeler wrote in the letter, which was passed to Mashable by a source that asked to remain unnamed.

The letter is one of the strongest indications yet that Wheeler intends to aggressively pursue Internet service providers — whether landline or telecom — that attempt to use network management as an excuse for throttling speeds.

Wheeler goes as far as to insinuate that the strategy of slowing the speeds of unlimited data customers has more to do with making money than handling its customer traffic.

"'Reasonable network management' concerns the technical management of your network; it is not a loophole designed to enhance your revenue streams. 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 in the letter, which can be found in its entirety at the bottom of this post.

The letter comes as the FCC is juggling a variety of considerations for how to effectively regulate the future of the Internet including broadband speeds, wireless spectrum, peering/interconnection and calls for enhanced net neutrality rules. Wheeler and the FCC have sought to allay concerns that the commission is either unwilling or unable to take action against service providers that are looking to squeeze money out of customers and content creators.

Verizon Wireless did not immediately respond to a request for comment.

Wheeler struck a stern tone in the letter, asking the company to clarify exactly why throttling a particular customer set will help handle network congestion.

The letter includes three questions:

"What is your rationale for treating customers differently based on the type of data plan to which they subscribe, rather than network architecture or technological factors?"

"Why is Verizon Wireless extending speed reductions from its 3G network to its much more efficient 4G LTE network?"

"How does Verizon Wireless justify this policy consistent with its continuing obligations under the 700 MHz C Block open platform rules, under which Verizon Wireless may not deny, limit, or restrict the ability of end users to download and utilize applications of their choosing on the C Block networks; how can this conduct be justified under the Commission's 2010 Open Internet rules, including the transparency rule that remains in effect?"

Unlimited data plans are something of a relic in the telecom industry. Data in the early days of cellphone and smartphone plans was an afterthought, an extra service that was added to text messages and voice minutes.

As smartphones evolved, telecom networks grew faster and content providers began to offer services like live streaming (it's football on your phone!), data use spiked. As a result, telecom companies have sought ways to transfer users to capped plan.

UPDATE: July 30, 5:27 pm EST: Verizon offered the following statement in response to the FCC's letter:





We will officially respond to the Chairman's letter once we have received and reviewed it. However, what we announced last week was a highly targeted and very limited network optimization effort, only targeting cell sites experiencing high demand. The purpose is to ensure there is capacity for everyone in those limited circumstances, and that high users don't limit capacity for others.

























Verizon Wireless Letter from the FCC