* https://www.ztecanada.com/products/zte-wireless-home-phone-w...
In the US, AT&T has such a service:
* https://www.att.com/device-support/article/wireless/KM126643...
Technically speaking, it is an "ATA", but you can't control the FXS port, as it's directly linked to the number associated with the SIM card.
Another solution would be using a cellular router in conjunction with a "normal" manageable ATA, which lets you configure the FXS port with a remote SIP account.
I think you can even find some stuff on ebay/aliexpress that combines both functionalities, but I never tried them (and would be worried of lack of support or firmware updates).
and verify the frequency support vs. what your area's cell towers use.
My experience has been that 'serving' over a cellular connection is dicey, and I've abandoned my quest to get static IPs on all of my cellular gateways. Peplink has a management portal that lets me control everything, including a built-in system to connect to web management portals behind the gateway.
PRI/T1 technology based on copper wires is being discontinued in much of the US right now, and consequently, demand for this kind of solution is going up