A.T.&T. has shut down its 3G wireless network as of February 22, 2022. T-Mobile will shut down its 3G network during the spring and summer of 2022, and Verizon has its 3G network shutdown date as December 31, 2022.
The FCC has more information and resources available at its 3G page. This transition may affect older smartphones, tablets, smart watches, vehicle GPS and road assistance devices, alarm systems, and medical devices. Some vehicles may also lose Automatic Crash Notification due to the 3G shutdown.