The latest is the TTGO T-Call, an ESP32 breakout board that also has a cellular modem. Yes, it’s only a 2G modem, but that still works in a lot of places, and the whole thing is $15. On board ...

There is also 8GB 8 MB of flash, double the amount on traditional WROOM modules. Mounting the device was a bit difficult since most ESP32 carrier boards will block some portion of the antenna array.