Data-only devices approved for use with GSMA flat-rate or unlimited plans

What data-only devices are approved for use with GSMA flat-rate or unlimited plans?

GSM-A utilizes LTE Bands: 2, 4 (66), 5, 12 (17), 14 (FirstNet), 29 and 30

Update June 9, 2020: Currently we are not accepting activations for Mikrotik devices with Category 6 LTE modems (LTE6, SXT6 etc) due to the chipset in use in these devices. Mikrotik devices with Category 4 LTE modems can still be activated.

Update April 21, 2020: Currently we are not accepting activations for the following TAC: 90008xx (ZTE Warp Hotspot). We are awaiting an update from the carrier as to whether they will activate these devices. We currently suspect compatibility issues. This list is subject to change and periodic updates.

Update April 16, 2020: Currently we are not accepting activations for the following TAC: 86164104 (Quectel EC-25 chipset) as it is not compatible with the plan we use. We are working with AT&T on a plan with similar specifications for these devices.

Update April 9, 2020: The "approved device" and "basic device" programmes on AT&T have been suspended until further notice; at this time all subscribers are being put on the same rate plan, rendering a list of approved/basic devices irrelevent.