MicroCell Service is Going Away VERY Soon
I just received my notice from AT&T that "We're shutting down our 3G service in February 2022 to make improvements to our network. This means that your MicroCell will not work on our enhanced network". WiFi-C (WiFi Calling) is what AT&T is suggesting to use to improve in-home coverage.
AT&T is rumored to be offering a new "MicroCell" which will supposedly be 4G/LTE and may eventually have 5G capabilities. Nothing is set in stone and nothing, other than the above is available publicly yet, and there is no ETA on when the new device will be available and what the purchase cost will be, so don't ask.