T-Mobile has already taken a few tentative steps toward shutting down Sprint's network following its acquisition of the operator in April.

"We've already done some on an isolated basis," T-Mobile CEO Mike Sievert said Tuesday during a UBS investor event.

However, Sievert said that T-Mobile likely will begin shutdown efforts in earnest starting in 2022, after it has successfully moved substantial amounts of customers and traffic onto its own network and off the aging Sprint network.

T-Mobile has made no secret of its plans to shutter Sprint's existing network as it moves through its five-year, $60 billion 5G network upgrade program. After all, there's no reason for T-Mobile to operate two separate wireless networks, and the company has boasted of up to $6 billion in savings via its merger with Sprint.

Moreover, Sprint's network won't be the first one T-Mobile has shut down. The operator dismantled the MetroPCS network following its acquisition of that regional network operator in 2012.

Even Sprint has experience in this area, having shuttered the WiMAX network it acquired from Clearwire in 2016.

In fact, Sprint's network isn't even the next wireless network to be shut down in the US. Verizon, for example, is scheduled to turn off service on its 3G network by the end of this year.

But T-Mobile's Sprint network shutdown project is perhaps the biggest one in recent wireless history, considering the roughly 50 million customers Sprint counted prior to the close of T-Mobile's acquisition of the company (many of those customers have phones that can also work on T-Mobile's network, which will likely smooth the transition).

T-Mobile officials have said the operator will work to migrate all of Sprint's customers onto its own network in the coming months and years, and that they will do so in ways that will reduce the number of customers who opt to leave the carrier completely.

"This same team has done it before with great success," Sievert said of the migration. "We're trying to move really, really quickly on this."

Sievert said T-Mobile is working to entice new customers to join the operator (and existing customers to stay) by building a cutting-edge 5G network with Sprint's 2.5GHz spectrum. Indeed, Sievert said the network can support peak speeds up to 1 Gbit/s.

Sievert said T-Mobile expects to cover 100 million people with 5G in 2.5GHz by the end of this year, and 200 million by the end of next year.

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