T-Mobile has announced it will be shutting down Sprint’s 3G and 4G networks as soon as next year, as it continues to migrate Sprint’s existing customer base to its own network. About 33% of Sprint’s legacy customers have already been shifted to T-Mobile’s network, with the Un-carrier aiming to complete the full transition by 2022.

T-Mobile confirmed to Light Reading that they plan to shutter Sprint’s LTE network by June 30, 2022. Meanwhile, the 3G CDMA network will be switched off on January 1, 2022. T-Mobile will utilize Sprint’s network assets to strengthen its 5G network. In fact, portions of the freed-up spectrum (n41 band) have already been deployed to support T-Mobile’s Ultra Capacity 5G coverage.

“We’ll ensure that we support our customers and partners through the transition. We began sending notifications late last year, and everyone who needs to act will be given advanced notice and hear directly from T-Mobile,” T-Mobile said on its website.

Most Sprint LTE phones will only need a SIM swap to work with T-Mobile’s LTE network. Devices that lack support for VoLTE or T-Mobile LTE won’t be able to connect to T-Mobile’s network after the deadline. T-Mobile says it will send out notifications to all users who need a new device or a SIM swap. If you’re a Sprint subscriber, you can go to T-Mobile’s IMEI check page to see if your phone is compatible with T-Mobile.

The Un-carrier also plans to shut off its own legacy 2G and 3G networks but says it hasn’t set a date in stone just yet. However, there are reports that it might happen in the first half of 2022.

Apart from T-Mobile, AT&T is another major US carrier that plans to pull the plug on its 3G network early next year. Meanwhile, Verizon will be joining both T-Mobile and AT&T in shutting down 3G in early 2023.