AT&T 3G network retirement plans
AT&T is no longer activating new 3G devices. Since February 2019 in the US they have started re-purposing their 3G frequency spectrum to 4G LTE or 5G by shutting down one of their two 3G bands (850MHz / 1900MHz).
After February 2019 services continue to be available in markets on a single band; only until such time when all 3G frequency spectrum gets reconfigured for 4G LTE or 5G use in that market. AT&T expects to complete their transition activities in all markets by February 2022.
It is highly recommended that you transition all your current solutions using 3G to 4G LTE as soon as possible as there may be no guarantee of continuing 3G network availability in your market in the coming days.
Check out the links below for more information available on this subject.