Last week it was reported that Netflix had begun posting on-screen messages blaming Verizon for congestion that was slowing video streams. While Netflix claims the message was simply one step in notifying customers about how an ISP can impact the viewing experience, Verizon described the move as “a PR stunt” and suggested the message “is not only inaccurate, it is deliberately misleading.” Later in the week, Verizon sent a cease and desist letter to Netflix.

“The Verizon network is crowded right now. Adjusting video for smoother playback,” read the Netflix message.

“The source of the congestion is almost certainly NOT congestion in Verizon’s network,” wrote David Young, who oversees federal regulatory affairs for Verizon, in a blog post. “Instead, the problem is most likely congestion on the connection that Netflix has chosen to use to reach Verizon’s network. Of course, Netflix is solely responsible for choosing how their traffic is routed into any ISP’s network.”

“Just weeks ago, Verizon and Netflix agreed that Netflix could pay Verizon to connect directly to its network, creating a faster connection that bypasses the go-between that carries most content through the Internet. Netflix previously entered one of those deals with Comcast,” reports The New York Times. This helped fuel the ongoing debate regarding Net neutrality.

In response to the messages, Verizon threatened to take legal action if Netflix does not stop blaming Verizon’s network for the poor service quality when streaming movies and TV shows.

Randal Milch, Verizon general counsel, sent a cease and desist letter to David Hyman, Netflix’s general counsel.

“Milch explains that there are a number of factors that contribute to performance of any service on the Internet, including interconnection between multiple networks on the Internet, in-home wiring, Wi-Fi and device settings and capabilities,” explains CNET. “He also adds in his letter that data from independent sources, such as the Federal Communications Commission, shows that Verizon FiOS consistently delivers network speeds that are in excess of advertised speeds.”

In his letter, Milch suggests that Netflix could improve its service delivery by making different business decisions and eliminating the “middlemen” used to send traffic to Verizon. “Responsibility for its customers’ experience falls squarely on Netflix itself,” he wrote.

“This is about consumers not getting what they paid for from their broadband provider,” a Netflix spokesman told CNET. “We are trying to provide more transparency, just like we do with the Netflix ISP Speed Index, and Verizon is trying to shut down that discussion.”