As Netflix debuts the hotly anticipated second season of Orange is the New Black, the site's dispute with Verizon Communications over streaming speeds is getting more heated.

Verizon, the fourth-largest internet service provider in the U.S., has sent a "cease and desist" letter to Netflix, telling the streaming giant to stop blaming it for slow speeds.

On Tuesday, Netflix customer and Vox Media designer Yuri Victor tweeted a screenshot of his Netflix player, which showed the message "The Verizon network is crowded right now. Adjusting video for smoother playback." Other users have reported seeing the same message, while some AT&T customers have seen similar messages. 

Netflix Verizon speeds

A screenshot of Verizon customer Yuri Victor's Netflix account, which says "The Verizon network is crowded right now". Verizon has told Netflix to 'cease and desist' blaming it for slow streaming speeds. (Yuri Victor/Twitter)

It's the latest in a bout of technological and verbal sparring between Netflix and U.S. internet service providers like Verizon.

Netflix's streaming service accounts for a third of all North American internet traffic during peak evening hours, according to Canadian networking services company Sandvine Inc.

Companies like Comcast and Verizon are asking Netflix to pay them extra. Netflix says their streaming data should be treated the same as any other content provider's.

In a blog post posted in March, CEO Reed Hastings wrote, "When an ISP sells a consumer a 10 or 50 megabits-per-second internet package, the consumer should get that rate, no matter where the data is coming from."

"This is about consumers not getting what they paid for from their broadband provider," Netflix Inc. said in a statement regarding Verizon's letter. "We are trying to provide more transparency ... and Verizon is trying to shut down that discussion."

"The impression that Netflix is falsely giving our customers is that the Verizon network is generally 'crowded' and troublesome," Verizon general counsel Randal Milch said in the letter. "Responsibility for its customers' experience falls squarely on Netflix itself ... The cost/quality trade-off is one Netflix has chosen."

Making a deal

In April, Netflix agreed to pay Verizon for a direct connection to its customers to improve delivery of its video. But Netflix still ranks Verizon's fibre-based FiOS service below nearly all major cable companies in its "ISP Speed Index," even though in overall speed tests, FiOS matches or exceeds cable modem download speeds in most areas.

According to Netflix's speed index, Verizon customers get Netflix content at an average of just under two megabits per second. That's just above the recommended speed of 1.5 mbps, which allows VHS-quality video, and well short the recommended speed of three mbps for DVD-quality video. The higher the speed, the better the video quality.

The current speeds for Verizon FiOS customers, as measured by Netflix, are below the average speeds for those customers received all last year.

Netflix also paid Comcast for a similar deal in February, after streaming speeds for Comcast subscribers hit the 1.5 mbps threshold in January.

But Netflix hasn't been happy about making those deals. In a blog post entitled "The Case Against ISP Tolls", Ken Florance, vice-president of content delivery at Netflix says Comcast is "double dipping" by charging Netflix to access its customers, and also by charging its customers to access content providers like Netflix.

The battle between Netflix and internet service providers is one of the primary battlegrounds in the larger debate over net neutrality, which has been hotly debated in Washington.

Net neutrality proponents say each piece of data should be treated equally by providers, no matter the source. ISPs say bandwidth hogs like Netflix should pay extra for ‘fast lane’ distribution to customers.

Better speeds in Canada

In Canada, streaming speeds on major broadband providers are, on average, better than in the U.S.

Netflix added Canada to its ISP speed index last month, with average streaming speeds in April of 2.52 Mbps, faster than the U.S. average of 2.33 Mbps. The one outlier in the Canadian rankings was Rogers, which placed last with average speeds of 1.67 Mbps, just above VHS quality.

According to a spokesman, Rogers says Netflix's tests were done "just before we virtually doubled Netflix capacity and we’ll continue to add more capacity as it’s needed."

The May results from Netflix's speed index are expected to be released in the next week.

Friday is the release of the second season of Orange is the New Black, a dark comedy set in a women's prison. It's also Netflix's second most popular original series after House of Cards

Netflix is expecting a boost in traffic this weekend as viewers binge-watch the show, and those viewers will be hoping they don't see any error messages.

with files from The Associated Press