Internet backbone provider Level 3 this week called out several major U.S. broadband providers for refusing to upgrade their networks in order to ease congestion.

"They are deliberately harming the service they deliver to their paying customers," Level 3 said. "They are not allowing us to fulfill the requests their customers make for content."

Level 3 helps Internet traffic get from point A to point B, but it works with other networks - 46,000 to be exact - to complete those connections so you can check your email, watch Netflix, access Google Drive, and post selfies to Instagram.

According to Level 3, however, some ISPs are not willing to spend the money on network upgrades that would ease congestion - and cut down on those Internet buffers. Why not? These companies, Level 3 said in a blog post, are located in markets where they do not face significant competition, suggesting there is no incentive to spend the money. Level 3 said a port upgrade would cost between $10,000 and $20,000.

"In countries or markets where consumers have multiple Broadband choices (like the UK) there are no congested peers," Level 3 said.

Level 3 declined to name the five U.S. broadband providers, but said they ranked "dead last in customer satisfaction across all industries in the U.S." in the 2013 American Customer Satisfaction Index.

Level 3 posted charts from a 100Gbps interconnect in Dallas with a port that was "congested and cannot accept all of the traffic that is trying to get through." Packets are dropped and those that are not dropped are delayed, Level 3 said. A 100Gbps port in Washington, D.C. with another peer, meanwhile, "shows no congestion."

"Shouldn't a broadband consumer network with near monopoly control over their customers be expected, if not obligated, to deliver a better experience than this?" the company asked.

Inter-connection, or peering, deals have been in the news recently after Netflix said that it was forced into such deals with ISPs like Comcast and Verizon. Without them, Netflix said, its customers would have a terrible experience using Netflix on those ISPs. Ideally, however, strong net neutrality rules would make such inter-connection deals obsolete, according to Netflix.

In response, the ISPs said such deals have been in place for years, and accused Netflix of trying to get something for nothing.

Level 3, meanwhile, had its own spat with Comcast four years ago. At the time, Level 3 accused Comcast of violating the principles of net neutrality when it demanded that Level 3 pay a recurring fee for transmitting online movies and other content to Comcast customers. Comcast responded that the deal it offered Level 3 is the same it offers its other content delivery providers, and accused Level 3 of wanting to double the amount of traffic it delivers to Comcast's network, for free. The companies reached a deal by July 2013, but terms of the settlement were not released.

Level 3 also battled with rival Cogent in 2005, when Level 3 cut off access to Cogent because of an ongoing dispute about financial arrangements.

As for net neutrality, the FCC is currently considering new rules, but at this point, inter-connection deals will not included. Essentially, the FCC wants to get its new rules in place as soon as possible, and wading into the peering issue would likely delay the process, so it's off the table for now.