T-Mobile unloaded on Dish Network in a new filing to the FCC.

"The message to Dish must continue to be: honor your agreement, take care of your customers, and go do your job," T-Mobile wrote. "Dish has the tools in its toolbox and the resources to take care of its wireless customers – it's time for it to start using them."

At issue is T-Mobile's decision to shut down Sprint's CDMA network by January 1, 2022. That decision is critical to Dish because it purchased around 9 million Sprint Boost Mobile customers from T-Mobile last year. Those customers are to remain on T-Mobile's network while Dish builds its own 5G network. However, many of those customers still own a CDMA phone and will need to get a new phone after January to remain connected.

"We expected to have at least another year before the CDMA shutdown," Stephen Stokols, the new chief executive of Dish's Boost Mobile phone brand, told Light Reading earlier this year.

In a recent filing with the FCC, Dish said a "majority" of its 9 million Boost subscribers are still on Sprint's CDMA network "and will be harmed if T-Mobile prematurely shuts down that network."

Continued Dish: "We believe that T-Mobile's actions raise significant competition and public interest concerns."

But T-Mobile said those claims are nothing but a "misinformation campaign" by Dish. Specifically, T-Mobile said the Master Network Services Agreement that T-Mobile, Dish and the Department of Justice signed in 2019 expressly states that "Dish is solely responsible for the migration of legacy network subscribers" and that "T-Mobile will provide Dish with reasonable advance notice of at least six months prior to the shutdown of the legacy network (CDMA network) in any market."

And that's exactly what it did, T-Mobile said. "In fact, T-Mobile provided Dish with fourteen months' advance notice (instead of the contractually mandated six)," the operator told the FCC.

T-Mobile added that it has made several attempts to help Dish migrate its Boost customers to T-Mobile's 5G network, offerings that Dish has rejected.

"Furthermore, Dish actually has been adding a substantial number of new customers onto the CDMA network each month and has extended the end date for new legacy Sprint network activations from January 1, 2021, to June 1, 2021, despite the fact that ceasing new CDMA activations would be a very simple step to take to move toward a timely migration," T-Mobile wrote.

Concluded T-Mobile: "Any lack of planning on its part is an issue that the Dish and Boost teams can and should promptly address."

After this article was published, Dish sent out this statement from Stokols: "No matter how T-Mobile tries to spin it, the simple fact remains: a shutdown of the Sprint CDMA network on January 1, 2022 is an attack on low-income consumers. T-Mobile’s accelerated shutdown of the CDMA network is motivated by greed, runs counter to the promises the company made to the government, and can only be explained as an anticompetitive action designed to undermine Dish as the nation’s fourth wireless carrier, harming consumers in the process."

Added Stokols: "T-Mobile used to be the 'uncarrier' that fought for customers. But, following its acquisition of Sprint, the combined company has transitioned to a 'heartless' behemoth."

T-Mobile, for its part, is moving full steam ahead to shutter Sprint's aging network and move the Sprint customers it acquired last year onto its new 5G network. Indeed, the company recently announced it would offer free 5G phones to new and existing customers, and would also move its existing customers on legacy pricing plans onto its new unlimited 5G data plans, at no extra cost.

Dish, meantime, has promised to start testing a 5G network in at least one major US city by the third quarter of this year.

Related posts:

— Mike Dano, Editorial Director, 5G & Mobile Strategies, Light Reading | @mikeddano