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 ...

A combination fax board and data modem available as an external unit that plugs into the serial port of the computer or as an expansion card for internal installation. It includes a switch that ...