Here in the United States, 3G networks are currently in the process of being shutdown as of November 2022, and I'm sure many of you out there reading this have heard about this in the news by now. AT&T shut their 3G network down back in February, T-Mobile shut theirs down in July, and Verizon is planning to shut theirs down on December 31st. This of course, means that 3G network phones and other 3G devices currently don't work anymore/won't work by 1/1/2023 (in the case of Verizon). In addition, AT&T shut down their 2G network in 2017, Verizon in 2020, and T-Mobile will do so this December.
It's a shame too, since there are many cool phones from the 2000s that have been/will be bricked by these shutdowns. :(