Usually it's considered good news when a company announces it is phasing out an old technology for a new one. But one network upgrade announced by Sprint sparked a lawsuit this week.

On Wednesday, two nonprofit Internet providers, Mobile Citizen and Mobile Beacon, filed a lawsuit against Sprint arguing that when the mobile carrier phases out an older 4G wireless technology called WiMAX for its more up-to-date LTE network, it will render a "near lethal blow" to the nonprofits' low-income Internet users. 

"Mobile Citizen and Mobile Beacon provide unlimited broadband service to 429 schools, 61 libraries and 1,820 nonprofit organizations across the country," wrote the nonprofit ISPs in their release announcing the lawsuit.

"But Sprint is planning to shut down the network these organizations rely on for Internet access by Nov. 6, and has failed to provide the means to transition their community of schools, libraries and nonprofit organizations onto a new network."

The history behind the spectrum spat is a little complicated. ISPs classified as Educational Broadband Service (EBS) providers by the FCC, which granted portions of the WiMAX spectrum to them. In turn, they leased out part of that spectrum to ISP Clearwire, on a 30-year deal that gave them the revenue to allow them to sell unlimited Internet service to low-income residents at a reduced rate.

But after Sprint bought Clearwire a couple of years ago, it decided to phase out the older WiMAX system for its next-gen LTE network. And along with Sprint's LTE network comes a 6GB data cap, after which the company throttles speeds.

"In the case of Mobile Beacon," the lawsuit states, "school modems use an average of 32 gigabytes (GBs) per month, with the top 25 percent using capacity between 50 and 300+ GBs per month. ... Moreover, overall non-profit usage averages of 43 GBs of capacity consumption per month; and in the case of Mobile Citizen the overall average broadband capacity consumption is 40 GB per month.

"Nonetheless, Clearwire and Sprint are curtailing that current level of capacity to a mere 6 GB monthly, which is a near lethal blow to plaintiffs' non-profit users," charges the suit, which is asking a Massachusetts state court to disallow Sprint from throttling LTE speeds after the 6GB data cap.

Even more problematic, according to nonprofits, is the fact that Sprint's transition is happening quickly: Most low-income customers will not have devices that work on the new LTE network, essentially leaving them abandoned without a connection they can use.

"As Sprint continues to shut down the Clearwire network, it leaves most of plaintiffs' customers with old devices on a network that is impaired and being phased out and no path to timely substitute a service," the lawsuit asserts. "When the Clearwire network is completely shut down, the vast majority of plaintiffs' customers will have no Internet service at all."

Founder of Mobile Citizen John Schwartz blasted what he sees as Sprint's hypocrisy in the matter.

"All Americans should have access to the Internet. That includes low-income Americans," he said. "Sprint has publicly professed a commitment to closing the digital divide. It must stop this injustice and stand up for the hundreds of thousands of children, families, teachers and community members who will be shut out of the American dream if they don't have access to the Internet."

Sprint replied to the lawsuit and the nonprofits' press statements in an email to Ars Technica, saying, "We do not offer unlimited data-only service to any customer. Yes, Sprint engages in reasonable network management practices as it is contractually entitled to do to ensure that their customers did not lose access in the middle of the month." And Sprint told TheVerge that around 75 percent of WiMAX users had completed the transition to LTE ahead of the shutoff deadline.

"We have repeatedly made attempts to discuss with [Mobile Citizen and Mobile Beacon] how we can best meet their end users' needs and resolve this matter. But instead of working it out like reasonable partners, they chose to file a complaint."

When Sprint shuts down the WiMAX network on Nov. 6, Mobile Citizen and Mobile Beacon say they expect some 300,000 people across the country to be affected.