AT&T Wireless on Mesa 3 Windows
1 Jul 2020
Update 11 Aug 2022 - If not able to connect automatically as explained below, please see Cellular modem troubleshooting on Mesa 3 Windows and Apply an APN with Skylight if needed.
AT&T has now uploaded the MS3 TAC number 01535600 to their system. This should allow a Mesa 3 Windows based device to activate through the AT&T Wireless consumer systems, providing access to consumer rate plans. Previously, AT&T had certified the MS3 as an enterprise platform only. Activating cellular service may still require some of the steps mentioned below. If you had previously activated a smartphone or enterprise plan, you may need to contact AT&T to switch to a consumer tablet data-only plan instead for it to work again.
Original article from 22 Jun 2020 -
OS release 20043 or higher must be installed on the Mesa 3 unit for the cellular modem to function properly. This OS uninstalls older cellular modem drivers and installs newer drivers.
As of 16 June 2020, AT&T data-only "tablet" plans may not be able to initially activate in the Mesa 3. We are working with AT&T to resolve this issue. In the mean time, a new Micro SIM card that has this plan may need to be initially activated in a Mesa 2 or other device then moved to the Mesa 3. Otherwise, you may need to use a "smartphone" plan instead in the Mesa 3.
After properly inserting an active Micro SIM card, you may need to reboot by tapping on Start > Power > Restart. After the reboot is complete, you may need to wait up to an additional 2 minutes for the cellular modem to complete powering on and connecting.
Sometimes Windows 10 is unable to automatically initiate the cellular data service. If this happens, you must uncheck "Let Windows keep me connected" under the Wireless icon in the task bar or "Let Windows manage this connection" under Start > Settings > Network & Internet > Cellular, then use the manual Disconnect and Connect buttons. This is as shown in the following images. You may need to wait 30 seconds after tapping Connect for the connection to complete fully. After you are connected, you may want to check the box again.
Windows may state that you need to enter a SIM PIN or manually apply APN settings. Most often using the manual Disconnect and Connect buttons as explained above will eliminate these messages. Only on rare occasions do you actually need to enter the default SIM PIN of 1111 or manually change or enter APN settings (sometimes you must switch them temporarily then change back). These are done under Start > Settings > Network & Internet > Cellular > Advanced options as shown in the following images.
If you have a specific Mesa 3 unit that will not activate any Micro SIM card from any cellular network provider, you may need to submit the unit for evaluation at a certified repair center.