T-Mobile plans to shutter its 3G CDMA network by January 1, 2022. However, the company has no firm date for when it will shut off its 2G GSM network.

"Devices that rely on 2G data will remain operational until that network sunsets at a later date," the company told Sen. Brian Schatz of Hawaii.

In response to questions, a T-Mobile representative explained to Light Reading that the company plans to shut down its 3G network next year because the spectrum it will gain from that effort will have a "significantly greater impact" in improving T-Mobile's LTE and 5G services when it is refarmed for that network.

Nonetheless, the topic is noteworthy considering Dish Network has embarked on a major policy and public relations campaign focused on reversing T-Mobile's decision to shutter the 3G CDMA network it acquired from Sprint last year. Dish is urging regulators to halt T-Mobile's shutdown plans because a number of Dish's Boost Mobile customers still use T-Mobile's CDMA network.

Dish acquired roughly 9 million Boost customers last year. The company will manage those customers on T-Mobile's network as a T-Mobile MVNO as it constructs its own 5G network.

T-Mobile's letter to Sen. Schatz was in response to questions from the senator about T-Mobile's plans to shut down its 3G CDMA network and whether that would affect customers who are struggling financially.

In its response, T-Mobile argued that it is working to transition affected customers over to its 4G LTE and 5G networks with offers of free phones and services at the same price or cheaper. T-Mobile also disclosed that "active 2G/3G devices accounted for less than 1% of traffic on the T-Mobile network as of the week of April 11, 2021." However, the company did not directly answer Sen. Schatz's question of how many T-Mobile customers currently rely on its 2G and 3G services.

T-Mobile isn't the only company facing Congressional questions about its network-shutdown plans. A group of senatorsm including Sen. Schatz, asked Verizon similar questions about its plans to shut down its 3G CDMA network by December 31, 2022. Verizon has not responded to repeated questions from Light Reading about whether it has responded to that letter. The senators asked Verizon to respond to their questions by May 3, 2021.

Verizon has delayed its 3G CDMA shutdown timeline several times. Indeed, the company told Mobile World Live in February that it would complete its 3G network shutdown by January 1, 2023, but then subsequently announced in a press release in March that it would complete that work by December 31, 2022.

Network shutdowns are relatively routine in the global wireless industry – after all, as wireless traffic increases, operators are keen to put their limited spectrum resources onto the most efficient transmission technology available. For example, AT&T discontinued service on its 2G wireless network on January 1, 2017. According to the operator's filings with the SEC around that time, it counted fully 4 million customers on its 2G network, the bulk of which were IoT devices. Additionally, Sprint recently shuttered its WiMAX network.

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