AT&T data enabled SIM card not working
19 May 2020
Original article from 13 Oct 2015, updated 19 May 2020:
AT&T originally stated that new 3G devices could no longer be activated on their network after 30 June 2019, though some activations may have been allowed until 19 Feb 2020. Also their 3G network would be sunset after 22 Feb 2022 to allow bandwidth to be re-allocated to their 4G and 5G networks.
AT&T Wireless offers many different data plans. Only certain data plans work with our rugged handheld computer products. A consumer "smartphone" or "tablet" data plan will most likely not work. The rugged handheld computer would more likely work with a "laptop modem" or "USB adapter" data plan instead, or a business account. If your AT&T SIM card will not enable cellular data on the rugged handheld computer, please contact AT&T to switch to a compatible "Data Connect for Mobile Hotspot and 4G devices" data plan or to obtain an alternative SIM card that has a compatible data plan enabled already.
Additional 3G Modem troubleshooting: