Verizon today demanded that "Netflix immediately cease and desist" its practice of telling customers that Verizon is to blame for network quality problems that affect streaming video.

This week, Netflix customer Yuri Victor tweeted a screenshot of a message he got from Netflix that said, "The Verizon network is crowded right now. Adjusting video for smoother playback..." It turns out Netflix has been providing these messages to customers of multiple ISPs for a month.

Verizon is worried that these notices will harm its otherwise sparkling reputation and even cause customers to switch Internet service providers. After all, the US Internet market is flush with competition, with every resident able to choose from so many high-quality service providers that there's no way we could list them all here.

"Netflix's false accusations have the potential to harm the Verizon brand in the marketplace," Verizon Executive VP and General Counsel Randal Milch wrote today in a letter to Netflix General Counsel David Hyman. "The impression that Netflix is falsely giving our customers is that the Verizon network is generally 'crowded' and troublesome. This could cause a customer to think that any attempted viewing of video, whether it be Hulu, YouTube or other sites, would yield a similarly 'crowded' experience, and he or she may then choose to alter or cease their use of the Verizon network."

Milch pointed out that Federal Communications Commission tests found that Verizon FiOS "consistently delivers speeds well in excess of advertised speeds, even during peak busy hour."

It's actually Netflix's fault that video isn't playing smoothly, he claimed, saying "Netflix relies on a panoply of content-distribution and other middle-man networks to reach its customers, trying to lower its costs as much as possible. The cost/quality trade-off is one Netflix has chosen. Netflix has been aware for some time that a few Internet middlemen have congestion issues with some IP networks and nonetheless, Netflix has chosen to continue sending its traffic over these congested routes. To now accuse last-mile ISPs of being solely responsible for service issues that may relate to congestion on peering circuits stemming from network arbitrage by upstream providers is self-serving, deceptive, inaccurate, and an unfair business practice."

Verizon, of course, successfully obtained payment from Netflix in exchange for a direct connection to its network. However, there could still be problems with Netflix video playback on Verizon's Internet service while the links between the two companies' networks are still being established.

"Our two companies recently completed a long-term, strategic agreement to bring Netflix content directly onto the Verizon network for the mutual benefit of both of our customers," Milch wrote. "I sincerely hope this is not a harbinger of things to come in terms of how Netflix treats its network partners and our mutual customers."

Although Netflix caved in to Verizon and Comcast's demands for payment, it has argued that the FCC should protect it from having to pay the ISPs for direct network connections.

Verizon wants details on every message Netflix has sent Verizon customers and specific details substantiating the claims that Verizon's network is at fault.

Milch described Verizon's demands as follows: "Verizon demands that Netflix immediately cease and desist from providing any such further 'notices' to users of the Verizon network. We further demand that within five days from the date of this letter that Netflix provide Verizon with any and all evidence and documentation that it possesses substantiating Netflix's assertion to Mr. Yuri Victor that his experience in viewing a Netflix video was solely attributable to the Verizon network, and that Netflix also provide a list of all Netflix customers on the Verizon network to whom Netflix has delivered such messages with the date and time that each such message was displayed for each user and the purported substantiation for it. Failure to provide this information may lead us to pursue legal remedies, and Verizon reserves all rights in that regard."

Netflix's notice to Victor didn't say exactly how it determined that the poor quality was the fault of Verizon's network. Analyst Dan Rayburn reported yesterday that Netflix sends the messages when it determines a customer is in an area where average bitrate is poor, where there is high congestion in which "the ratio between peak and through traffic is abnormally compressed," and where a high percentage of streaming sessions go through a "rebuffer."

In response to Verizon's cease and desist letter, a Netflix spokesperson said, "This is about consumers not getting what they paid for from their broadband provider. We are trying to provide more transparency, just like we do with the ISP Speed Index, and Verizon is trying to shut down that discussion."